Protein A Chromatography Purification for a Monoclonal Antibody from Process Development to Scale-up

Research Article | DOI: https://doi.org/10.31579/2690-1919/285

Protein A Chromatography Purification for a Monoclonal Antibody from Process Development to Scale-up

  • Dilara Bas 1*
  • Emre Burak Erkal 1
  • Melis Korkmaz 1
  • Ali Recepoglu 1
  • Hazal Elitas 1
  • Deniz Baycin Demirhan 1

1 Biotechnology Group, Turgut Pharmaceuticals, İstanbul, Turkey        

*Corresponding Author: Dilara Bas, Turgut Pharmaceuticals, Biotechnology Group, İstanbul, Turkey

Citation: Dilara Bas, Emre Burak Erkal, Melis Korkmaz, Ali Recepoglu, Hazal Elitas, Deniz Baycin Demirhan. (2022). Protein A Chromatography Purification for a Monoclonal Antibody from Process Development to Scale-up. J Clinical Research and Reports, 12(2); DOI:10.31579/2690-1919/285

Copyright: © 2022 Dilara Bas. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 24 August 2022 | Accepted: 28 October 2022 | Published: 16 November 2022

Keywords: protein a chromatography; monoclonal antibody; high-throughput screening; design of experiments; scale-up; manufacturing

Abstract

Monoclonal antibodies have been established as a major product class of biotechnology-based drugs. The increasing demand of monoclonal antibodies has led pharmaceutical companies to adopt efficient production processes. Transferring monoclonal antibody production to the industrial manufacturing requires adequate effort in process development. 

The strategy to reduce development time and cost comprises high-throughput process development which is especially central for the rapid optimization of the purification process. Chromatography process is the backbone of the purification process that can deliver high purity but it requires significant resources. Combined with high-throughput process development approach, the chromatography process is easy to develop and scale-up from laboratory to manufacturing scale. Design of experiments helps high-throughput process development workflow to provide decision-support techniques. This approach ensures significantly decreased time and material needs while improving the chromatography process. 

Protein A affinity chromatography is one of the most important chromatographic steps because of its great performance and capabilities. Most of the working parameters can be predefined and are identical for several monoclonal antibodies. However, some parameters like elution pH, loading capacity, resin type need further optimization for each monoclonal antibody. 

In this study, the loading and elution parameters were screened for Protein A chromatography to identify the best purification conditions using the combination of Design of Experiments and high-throughput process development approach in micro-volume columns. Developed working parameters were used for scale-up and tested under robust process conditions. Specific chromatography conditions were applied in pilot-scale and data comparison was done with micro-volume columns, lab-column scale to validate high-throughput strategy approach

Abbreviations

AEX : Anion Exchange Chromatography 

CHO: Chinese Hamster Ovary 

DoE: Design of Experiments; 

DBC: Dynamic Binding Capacity; 

HTPD: High-throughput Process Development; 

HMW: High Molecular Weight; 

HCPs: Host Cell Proteins; 

mAbs: Monoclonal Antibody; 

MMC: Mixed-Mode Chromatography PA: Protein A; 

rPA: Residual Protein A. 

Introduction

Monoclonal antibody (mAb)-based drugs have become great tools to effectively treat many diseases such as cancer, rheumatic diseases, viral diseases, and other nervous system pathologies [1,2]. These are target specific parts of unregulated pathways and interfere with immunological processes [2]. Purification of mAbs is performed on standardized platforms including centrifugation, filtration, chromatography, virus inactivation. During production and purification of mAbs, impurities are encountered which can result from product itself and the process. Product impurities are aggregates and post-translational modifications [3, 4] whereas host cell proteins (HCPs), residual DNA (rDNA) or Protein A are process impurities [4, 5]. Protein A chromatography is the initial capture step in manufacturing of mAbs and process impurities like HCPs and rDNA are generally removed during this step [3, 6, 7]. Protein A purification depends on the highly specific interactions between the Fc region of the mAb and the Protein A resin. 

Purification process starts by loading the supernatant to the column at neutral pH. Then, wash step is applied to get rid of impurities such as HCPs, rDNA and the mAb is eluted by decreasing the buffer pH [8]. A process flowchart for a typical Protein A chromatography is shown Figure 1. 

Figure 1: Process Flowchart for Protein A Chromatography

95-99% yield and >70% volume reduction can be achieved through Protein A chromatography. After the capture process, polishing steps like ion exchange chromatography or mixed-mode chromatography (MMC) are applied in the purification platform to remove the remaining impurity traces as well as residual Protein A (rPA) [9, 10]. 

High-throughput process development (HTPD) defines to increase the number of experiments while using significantly decreased time and material consumption compared to traditional development. Instead of laboratory column scale, the process parameters and sensitivity can be identified by micro-volume columns with high-throughput chromatography approach. With HTPD, Design of Experiments (DoE) is a systematic and efficient method to find optimum process conditions [11]. This combination has been successfully used for characterization of purification step performance with process parameters like working pH, loading percentage and process performance [3]. It also provides a representative model for understanding of manufacturing process. 

After the determination of the operating process parameters with high-throughput chromatography approach, lab-scale column trials are applied for optimization and evaluation of the robustness of the process parameters as well as of the impurity levels [12]. 

Scale-up of chromatographic purification is applied by increasing the column diameter and volumetric flow rate while bed height and linear flow rate are constant. For the determination of the column diameter, production volume and loading volume need to be estimated in order to use optimal volume of the related resin [13]. During this, reproducibility of the process and impurity levels are compared [14]. When scale-up studies are deemed successful by the comparison of scale-up and lab-scale column studies using a full analytical data set, the chromatography process can be considered ready for full-scale manufacturing. General concept of scale-up for mAb chromatography process is shown in Figure 2.

Figure 2: Scale-up strategy for chromatography

The study of parameters such as dynamic binding capacity (DBC), flow rate and type & pH of elution or wash buffers are important for Protein A chromatography design. DBC shows the maximum amount of protein which can be loaded onto the resin. Combination of DBC and flow conditions is useful for avoiding product loss [15]. Other study parameters such as lifetime of the resin, wash buffer condition, cleaning or sanitization procedures are also considered to evaluate of Protein A chromatography process [15,16].

In this work, Protein A resin and parameter screening was performed with HTPD technology. Resin type, loading and elution conditions were identified using combinations with DoE to use scale-up studies. During scale-up studies, different loading strategies were tested to create robust process conditions. Optimized working parameters were applied in pilot-scale and data comparison was done with micro-volume columns and lab-column scale.

Material and Methods

1. Protein A Resin and Parameter Screening with High-Throughput Chromatography

Monoclonal antibody, IgG1 (pI: 8 - 8.5), was produced using recombinant Chinese Hamster Ovary (CHO) cells. CHO cells were grown in Mobius® 3L single-use bioreactors (Merck KGaA, Darmstadt, Germany) with the following set points: pH 7 - 7.1, 37 °C, dissolved oxygen between 30-60 % of air. Clarified CHO cell culture supernatant was achieved with Millistak+® Pod Disposable Depth Filter System (Merck KGaA, Darmstadt, Germany) with a concentration of 2.55 mg/ml.  Protein A resin and parameter screening parameters were designed with Design Expert Software 12 (Stat-Ease, Inc., Minneapolis, MN). Response surface modeling with L-optimal approach was used. Factors entered in the software were as follows: elution pH (3.20 - 3.60) at 0.1 M acetic acid, loading percentage between 40%-80% and resin type. Responses were set as yield and HCPs. 100 µl (0.5 cm x 0.5 cm) OPUS® PipetColumns (Repligen Corporation) were used for screening with electronic Multipipette® E3x (Eppendorf). PipetColumns, which are also called micro-volume columns, containing eight various types of Protein A (PA) resins were used for screening. During loading step, DBC data was used for each resin from previous studies. Flow rate was 4µl/sec at a residence time of 25 sec. Micro-volume columns were washed with 20 mM sodium phosphate, 1 M NaCl pH 6 and 20mM sodium phosphate pH 7 at 5 CV, respectively. 

2. Confirmation Runs with Scale-up Studies

After screening, prediction of implementation deduced from Protein A resin and parameter screenings was done by performing chromatography runs with (1.13 cm x 10 cm) 10 ml pre-packed column and (44 cm x 10 cm) 80 ml packed column. The resin was packed into Vantage® L Laboratory Column (Merck KGaA, Darmstadt, Germany), according to the instruction of the vendor. DBC was performed with related Protein A column at a residence time of 6 minutes. Working template which comes from screening was adapted on both ÄKTA Avant 25 and ÄKTA Avant 150, except elution pH and loading percentage. A different loading percentage for worst-case scenarios was applied in 80 ml packed column, only. The loading strategy is shown in Table 1.  CHO supernatant had a concentration of 1.90 mg/ml for 10 ml pre-packed column whereas 1.03 mg/ml for 80 ml packed column. 

Table 1: The loading strategy plan with loading percentages

3. Pilot-Scale Studies

Two manufacturing scale, called as non-GMP (1) and non-GMP (2), Protein A chromatography runs were conducted with Mobius® Flex Ready Solution using Smart Flexware™ Assemblies for Chromatography. CHO cells were grown in Mobius® 200 L single-use bioreactors (Merck KGaA, Darmstadt, Germany). Supernatants from two bioreactors were used for Protein A chromatography. Clarification was performed with Mobius® FlexReady Solution for Large Scale Clarification (Merck KGaA, Darmstadt, Germany) with a concentration of 0.94 mg/ml and 1.19 mg/ml, respectively. Prepacked column (Repligen Corporation) was used for Protein A chromatography at the pilot-scale production. Manufacturing runs were applied in a similar fashion to the confirmation run template.

4. Analytical Characterization

Nano Drop™ One (Thermo Fisher Scientific) was used to measure mAb concentration using 280 nm. SE-UPLC (Waters Corporation) was performed to measure aggregates, high molecular weight percentage (HMW %) with BEH SEC200 (4.6 x 300 mm. 1.7 µm. 200 Å), (Waters Corporation) and 20 mM Phosphate Buffer, 188 mM NaCl, pH 7.4 mobile phase. Flow rate was 0.25 ml/min and qualified using reference mAb. CHO HCPs were measured using ELISA method using Cygnus kit with sample diluent (Cat. #I028), (#F550, Cygnus Technologies, Southport, NC). Another Cygnus kit (#F600, Cygnus Technologies, Southport, NC) was used to measure residual Protein A .

Results and Discussion

1. Protein A Resin and Parameter Screening with High-Throughput Chromatography

After designing with the software, a total of 37 experiments were run and analysis were transferred to Analysis of Variance (ANOVA) in the DoE software. During analysis, the target for HCP value was minimized to reduce impurities whereas yield was maximized for the achievement of the process. The importance of responses for both HCP and yield were selected as high (5 point). The supernatant CHO HCP value was 4675243 ppm. The solution from DoE software with desirability was shown in Figure 3.

Figure 3: The solution parameters from DoE for Protein A chromatography

Protein A chromatography is the best first capture step for mAb purification due to high selectivity and yielding high purity. For subtypes of IgG1, Protein A chromatography is preferable [17]. Increased usage of Protein A resins has resulted in the emergence of variety of Protein A resins to the market. Therefore, evaluation of the performance of Protein A resins has become very important. 

The aim of Protein A resin screening was to find the best resin type amongst eight different Protein A resins using micro-volume columns. This study helped to select the suitable resin type for the relevant-mAb. Protein A resins comprise of a base matrix and ligands which are classified as native or recombinant, extracted from Staphylococcus aureus or expressed in Escherichia coli, respectively [18]. The type of the base matrix and Protein A ligand is very essential for Protein A chromatography. The results showed that the best resin type is PA 5 for the mAb used in this study. PA 5 has an agarose-based base matrix. It gives high stability, binding capability, and reduction of impurities (HCPs) during purification [19].

Elution of the product from Protein A resin, which is essentially the reverse process of binding, was carried out using a low pH buffer. pH elution affects the binding sites directly by reducing their affinity. This principle is the most common way to elute the mAb from the resin. During the screening of elution conditions, pH value range was kept narrow to find the best elution condition that is suitable for the base matrix and Protein A ligand.

The feed composition effect on Protein A resin impacts HCPs. Also, the number of HCPs is associated with the resin life-time performance. After loading the column, HCP clearance is maximized with washing steps. First, washing buffer with high ionic strength was applied for HCPs reduction. Then, second wash was applied with neutral pH and low ionic strength to maximize clearance without disrupting the interaction between mAb and Protein A ligand [1]. 

The results showed that resin type is significantly affecting the process (p < 0>

Parameter screening of the purification process for mAbs requires the consideration of many parameters like removal of impurities and ready suitability of large-scale production. DoE offered screening, optimization, and design of robust parameters. After 37 experiments, the best parameters for Protein A chromatography were selected as in the range for DoE analysis as following: 0.1 M acetic acid pH 3.2. During the selection of best parameters, removal of impurities and yield was considered. Experimental template with results is given in Supplementary Data.

Supplementary Data

Experimental template with results for Protein A Resin and Parameter Screening

2. Confirmation Runs with Scale-up Studies

Firstly, the solution offered by the DoE software was performed with a 10 ml pre-packed column (1.13 cm x 10 cm). During the confirmation run, residence time was selected as 6 minutes since back pressure in the column may occur during loading if a shorter residence time is used, which may lead to product loss at the industry scale. Therefore, DBC was calculated at a residence time of 6 minutes before the confirmation runs, as it depends on residence time, based on product loading time and flow-rate. In industrial scale, product loading is applied as between 70-80% of their DBC due to safety factor and protection of resin life-time [20]. The results showed that confirmation runs results were similar for, HCPs, HMW% and yield (Figure 4) meaning that the designed model is suitable for process development platform.

Figure 4: The confirmation runs results for 10 ml pre-packed column (1.13 cm x 10 cm)

The manufacturing scale purification process has limitations affecting the production capacity. For chromatography, these limitations are overcome by controlling the working pH, flow rate, temperature, and buffer volume [21]. Loading percentage is the major consideration since it is defining the process performance and the quality of the mAb. Therefore, a different loading strategy was performed with 80 ml packed column (44 cm x 10 cm) to overcome this limitation. This work-process can be also called a “worst-case scenario”.

The results for 80 ml packed column (44 cm x 10 cm) shown in Figure 5 demonstrated that loading percentage should be considered because it affects the production plant in means of mAb-based drug yield per batch and manufacturing costs. Thus, the manufacturing scale of a specific mAb should be designed stable considering loading percentage. 

Figure 5: The results for different loading percentages in Protein A chromatography

Scale-up process has some considerations for the manufacturing of mAbs.  For purification, the usage of endotoxin free components and implementation of viral clearance steps are the key factors of the manufacturing, and they should be controlled and monitored for scale-up studies. 

Chromatography process has other considerations during scale-up. The chromatographic resins should be chemically and physically robust and easy to clean. The resin life-time should also be determined for purification safety [25, 26]. 

Column packing at the pilot scale has some disadvantages; since higher pressure drops, and foaming can occur because the resin is agitated during the packing. Bed height instability is also another concern. Prepacked columns are easy to set up, validate and clean during the pilot-scale production. Therefore, a prepacked column was used for Protein A chromatography at pilot-scale [27].

Pilot-scale chromatography systems are automated systems with sensors, air detectors and valves. These systems may increase dead volumes which can affect the yield achieved when compared with the purification step at small-scales [27]. This issue was observed in 200 L non-GMP (2) Cycle 2- Yield (84%). 

Conclusion

The increasing demand of mAb-based pharmaceuticals have led the development of Protein A chromatography to become very crucial. For this reason, it is very essential to develop an effective process in a fast manner. Using micro-volume columns combined with DoE provided screening of Protein A resins and parameters in a short time. In this study, firstly, Protein A resin and parameter screening was performed to be used in a unique mAb production. PA 5 resin which has an agarose-based base matrix was selected as a suitable resin with the parameters of 0.1 M acetic acid pH 3.2. These conditions were applied from the laboratory scale to the pilot-scale for Protein A chromatography. Comparability between laboratory scale and pilot-scale was also observed. HTPD strategy was combined with DoE, Protein A resin and parameters were found for efficient Protein A chromatography. The purpose of confirmation runs was to scout appropriate parameters for manufacturing scale. Therefore, these runs were performed before scaling up. Protein A resin and parameters were found to be suitable for scaling up. Regarding to this, non-GMP studies were achieved successfully to produce unique mAb

Acknowledgements

The authors thank Ahmet Emin Atik, Yiğit Erdemgil and Zeynep Zülfiye Yıldırım Keleş for the analytical characterization support. Special thanks are given to the Chairman of the Board and General Manager Tunç Turgut from Turgut Pharmaceuticals.

Conflict of interest

The authors have no conflicts of interest to declare.

References

Clearly Auctoresonline and particularly Psychology and Mental Health Care Journal is dedicated to improving health care services for individuals and populations. The editorial boards' ability to efficiently recognize and share the global importance of health literacy with a variety of stakeholders. Auctoresonline publishing platform can be used to facilitate of optimal client-based services and should be added to health care professionals' repertoire of evidence-based health care resources.

img

Virginia E. Koenig

Journal of Clinical Cardiology and Cardiovascular Intervention The submission and review process was adequate. However I think that the publication total value should have been enlightened in early fases. Thank you for all.

img

Delcio G Silva Junior

Journal of Women Health Care and Issues By the present mail, I want to say thank to you and tour colleagues for facilitating my published article. Specially thank you for the peer review process, support from the editorial office. I appreciate positively the quality of your journal.

img

Ziemlé Clément Méda

Journal of Clinical Research and Reports I would be very delighted to submit my testimonial regarding the reviewer board and the editorial office. The reviewer board were accurate and helpful regarding any modifications for my manuscript. And the editorial office were very helpful and supportive in contacting and monitoring with any update and offering help. It was my pleasure to contribute with your promising Journal and I am looking forward for more collaboration.

img

Mina Sherif Soliman Georgy

We would like to thank the Journal of Thoracic Disease and Cardiothoracic Surgery because of the services they provided us for our articles. The peer-review process was done in a very excellent time manner, and the opinions of the reviewers helped us to improve our manuscript further. The editorial office had an outstanding correspondence with us and guided us in many ways. During a hard time of the pandemic that is affecting every one of us tremendously, the editorial office helped us make everything easier for publishing scientific work. Hope for a more scientific relationship with your Journal.

img

Layla Shojaie

The peer-review process which consisted high quality queries on the paper. I did answer six reviewers’ questions and comments before the paper was accepted. The support from the editorial office is excellent.

img

Sing-yung Wu

Journal of Neuroscience and Neurological Surgery. I had the experience of publishing a research article recently. The whole process was simple from submission to publication. The reviewers made specific and valuable recommendations and corrections that improved the quality of my publication. I strongly recommend this Journal.

img

Orlando Villarreal

Dr. Katarzyna Byczkowska My testimonial covering: "The peer review process is quick and effective. The support from the editorial office is very professional and friendly. Quality of the Clinical Cardiology and Cardiovascular Interventions is scientific and publishes ground-breaking research on cardiology that is useful for other professionals in the field.

img

Katarzyna Byczkowska

Thank you most sincerely, with regard to the support you have given in relation to the reviewing process and the processing of my article entitled "Large Cell Neuroendocrine Carcinoma of The Prostate Gland: A Review and Update" for publication in your esteemed Journal, Journal of Cancer Research and Cellular Therapeutics". The editorial team has been very supportive.

img

Anthony Kodzo-Grey Venyo

Testimony of Journal of Clinical Otorhinolaryngology: work with your Reviews has been a educational and constructive experience. The editorial office were very helpful and supportive. It was a pleasure to contribute to your Journal.

img

Pedro Marques Gomes

Dr. Bernard Terkimbi Utoo, I am happy to publish my scientific work in Journal of Women Health Care and Issues (JWHCI). The manuscript submission was seamless and peer review process was top notch. I was amazed that 4 reviewers worked on the manuscript which made it a highly technical, standard and excellent quality paper. I appreciate the format and consideration for the APC as well as the speed of publication. It is my pleasure to continue with this scientific relationship with the esteem JWHCI.

img

Bernard Terkimbi Utoo

This is an acknowledgment for peer reviewers, editorial board of Journal of Clinical Research and Reports. They show a lot of consideration for us as publishers for our research article “Evaluation of the different factors associated with side effects of COVID-19 vaccination on medical students, Mutah university, Al-Karak, Jordan”, in a very professional and easy way. This journal is one of outstanding medical journal.

img

Prof Sherif W Mansour

Dear Hao Jiang, to Journal of Nutrition and Food Processing We greatly appreciate the efficient, professional and rapid processing of our paper by your team. If there is anything else we should do, please do not hesitate to let us know. On behalf of my co-authors, we would like to express our great appreciation to editor and reviewers.

img

Hao Jiang

As an author who has recently published in the journal "Brain and Neurological Disorders". I am delighted to provide a testimonial on the peer review process, editorial office support, and the overall quality of the journal. The peer review process at Brain and Neurological Disorders is rigorous and meticulous, ensuring that only high-quality, evidence-based research is published. The reviewers are experts in their fields, and their comments and suggestions were constructive and helped improve the quality of my manuscript. The review process was timely and efficient, with clear communication from the editorial office at each stage. The support from the editorial office was exceptional throughout the entire process. The editorial staff was responsive, professional, and always willing to help. They provided valuable guidance on formatting, structure, and ethical considerations, making the submission process seamless. Moreover, they kept me informed about the status of my manuscript and provided timely updates, which made the process less stressful. The journal Brain and Neurological Disorders is of the highest quality, with a strong focus on publishing cutting-edge research in the field of neurology. The articles published in this journal are well-researched, rigorously peer-reviewed, and written by experts in the field. The journal maintains high standards, ensuring that readers are provided with the most up-to-date and reliable information on brain and neurological disorders. In conclusion, I had a wonderful experience publishing in Brain and Neurological Disorders. The peer review process was thorough, the editorial office provided exceptional support, and the journal's quality is second to none. I would highly recommend this journal to any researcher working in the field of neurology and brain disorders.

img

Dr Shiming Tang

Dear Agrippa Hilda, Journal of Neuroscience and Neurological Surgery, Editorial Coordinator, I trust this message finds you well. I want to extend my appreciation for considering my article for publication in your esteemed journal. I am pleased to provide a testimonial regarding the peer review process and the support received from your editorial office. The peer review process for my paper was carried out in a highly professional and thorough manner. The feedback and comments provided by the authors were constructive and very useful in improving the quality of the manuscript. This rigorous assessment process undoubtedly contributes to the high standards maintained by your journal.

img

Raed Mualem

International Journal of Clinical Case Reports and Reviews. I strongly recommend to consider submitting your work to this high-quality journal. The support and availability of the Editorial staff is outstanding and the review process was both efficient and rigorous.

img

Andreas Filippaios

Thank you very much for publishing my Research Article titled “Comparing Treatment Outcome Of Allergic Rhinitis Patients After Using Fluticasone Nasal Spray And Nasal Douching" in the Journal of Clinical Otorhinolaryngology. As Medical Professionals we are immensely benefited from study of various informative Articles and Papers published in this high quality Journal. I look forward to enriching my knowledge by regular study of the Journal and contribute my future work in the field of ENT through the Journal for use by the medical fraternity. The support from the Editorial office was excellent and very prompt. I also welcome the comments received from the readers of my Research Article.

img

Dr Suramya Dhamija

Dear Erica Kelsey, Editorial Coordinator of Cancer Research and Cellular Therapeutics Our team is very satisfied with the processing of our paper by your journal. That was fast, efficient, rigorous, but without unnecessary complications. We appreciated the very short time between the submission of the paper and its publication on line on your site.

img

Bruno Chauffert

I am very glad to say that the peer review process is very successful and fast and support from the Editorial Office. Therefore, I would like to continue our scientific relationship for a long time. And I especially thank you for your kindly attention towards my article. Have a good day!

img

Baheci Selen

"We recently published an article entitled “Influence of beta-Cyclodextrins upon the Degradation of Carbofuran Derivatives under Alkaline Conditions" in the Journal of “Pesticides and Biofertilizers” to show that the cyclodextrins protect the carbamates increasing their half-life time in the presence of basic conditions This will be very helpful to understand carbofuran behaviour in the analytical, agro-environmental and food areas. We greatly appreciated the interaction with the editor and the editorial team; we were particularly well accompanied during the course of the revision process, since all various steps towards publication were short and without delay".

img

Jesus Simal-Gandara

I would like to express my gratitude towards you process of article review and submission. I found this to be very fair and expedient. Your follow up has been excellent. I have many publications in national and international journal and your process has been one of the best so far. Keep up the great work.

img

Douglas Miyazaki

We are grateful for this opportunity to provide a glowing recommendation to the Journal of Psychiatry and Psychotherapy. We found that the editorial team were very supportive, helpful, kept us abreast of timelines and over all very professional in nature. The peer review process was rigorous, efficient and constructive that really enhanced our article submission. The experience with this journal remains one of our best ever and we look forward to providing future submissions in the near future.

img

Dr Griffith

I am very pleased to serve as EBM of the journal, I hope many years of my experience in stem cells can help the journal from one way or another. As we know, stem cells hold great potential for regenerative medicine, which are mostly used to promote the repair response of diseased, dysfunctional or injured tissue using stem cells or their derivatives. I think Stem Cell Research and Therapeutics International is a great platform to publish and share the understanding towards the biology and translational or clinical application of stem cells.

img

Dr Tong Ming Liu

I would like to give my testimony in the support I have got by the peer review process and to support the editorial office where they were of asset to support young author like me to be encouraged to publish their work in your respected journal and globalize and share knowledge across the globe. I really give my great gratitude to your journal and the peer review including the editorial office.

img

Husain Taha Radhi

I am delighted to publish our manuscript entitled "A Perspective on Cocaine Induced Stroke - Its Mechanisms and Management" in the Journal of Neuroscience and Neurological Surgery. The peer review process, support from the editorial office, and quality of the journal are excellent. The manuscripts published are of high quality and of excellent scientific value. I recommend this journal very much to colleagues.

img

S Munshi

Dr.Tania Muñoz, My experience as researcher and author of a review article in The Journal Clinical Cardiology and Interventions has been very enriching and stimulating. The editorial team is excellent, performs its work with absolute responsibility and delivery. They are proactive, dynamic and receptive to all proposals. Supporting at all times the vast universe of authors who choose them as an option for publication. The team of review specialists, members of the editorial board, are brilliant professionals, with remarkable performance in medical research and scientific methodology. Together they form a frontline team that consolidates the JCCI as a magnificent option for the publication and review of high-level medical articles and broad collective interest. I am honored to be able to share my review article and open to receive all your comments.

img

Tania Munoz

“The peer review process of JPMHC is quick and effective. Authors are benefited by good and professional reviewers with huge experience in the field of psychology and mental health. The support from the editorial office is very professional. People to contact to are friendly and happy to help and assist any query authors might have. Quality of the Journal is scientific and publishes ground-breaking research on mental health that is useful for other professionals in the field”.

img

George Varvatsoulias

Dear editorial department: On behalf of our team, I hereby certify the reliability and superiority of the International Journal of Clinical Case Reports and Reviews in the peer review process, editorial support, and journal quality. Firstly, the peer review process of the International Journal of Clinical Case Reports and Reviews is rigorous, fair, transparent, fast, and of high quality. The editorial department invites experts from relevant fields as anonymous reviewers to review all submitted manuscripts. These experts have rich academic backgrounds and experience, and can accurately evaluate the academic quality, originality, and suitability of manuscripts. The editorial department is committed to ensuring the rigor of the peer review process, while also making every effort to ensure a fast review cycle to meet the needs of authors and the academic community. Secondly, the editorial team of the International Journal of Clinical Case Reports and Reviews is composed of a group of senior scholars and professionals with rich experience and professional knowledge in related fields. The editorial department is committed to assisting authors in improving their manuscripts, ensuring their academic accuracy, clarity, and completeness. Editors actively collaborate with authors, providing useful suggestions and feedback to promote the improvement and development of the manuscript. We believe that the support of the editorial department is one of the key factors in ensuring the quality of the journal. Finally, the International Journal of Clinical Case Reports and Reviews is renowned for its high- quality articles and strict academic standards. The editorial department is committed to publishing innovative and academically valuable research results to promote the development and progress of related fields. The International Journal of Clinical Case Reports and Reviews is reasonably priced and ensures excellent service and quality ratio, allowing authors to obtain high-level academic publishing opportunities in an affordable manner. I hereby solemnly declare that the International Journal of Clinical Case Reports and Reviews has a high level of credibility and superiority in terms of peer review process, editorial support, reasonable fees, and journal quality. Sincerely, Rui Tao.

img

Rui Tao

Clinical Cardiology and Cardiovascular Interventions I testity the covering of the peer review process, support from the editorial office, and quality of the journal.

img

Khurram Arshad

Clinical Cardiology and Cardiovascular Interventions, we deeply appreciate the interest shown in our work and its publication. It has been a true pleasure to collaborate with you. The peer review process, as well as the support provided by the editorial office, have been exceptional, and the quality of the journal is very high, which was a determining factor in our decision to publish with you.

img

Gomez Barriga Maria Dolores

The peer reviewers process is quick and effective, the supports from editorial office is excellent, the quality of journal is high. I would like to collabroate with Internatioanl journal of Clinical Case Reports and Reviews journal clinically in the future time.

img

Lin Shaw Chin

Clinical Cardiology and Cardiovascular Interventions, I would like to express my sincerest gratitude for the trust placed in our team for the publication in your journal. It has been a true pleasure to collaborate with you on this project. I am pleased to inform you that both the peer review process and the attention from the editorial coordination have been excellent. Your team has worked with dedication and professionalism to ensure that your publication meets the highest standards of quality. We are confident that this collaboration will result in mutual success, and we are eager to see the fruits of this shared effort.

img

Maria Dolores Gomez Barriga

Dear Dr. Jessica Magne, Editorial Coordinator 0f Clinical Cardiology and Cardiovascular Interventions, I hope this message finds you well. I want to express my utmost gratitude for your excellent work and for the dedication and speed in the publication process of my article titled "Navigating Innovation: Qualitative Insights on Using Technology for Health Education in Acute Coronary Syndrome Patients." I am very satisfied with the peer review process, the support from the editorial office, and the quality of the journal. I hope we can maintain our scientific relationship in the long term.

img

Dr Maria Dolores Gomez Barriga

Dear Monica Gissare, - Editorial Coordinator of Nutrition and Food Processing. ¨My testimony with you is truly professional, with a positive response regarding the follow-up of the article and its review, you took into account my qualities and the importance of the topic¨.

img

Dr Maria Regina Penchyna Nieto

Dear Dr. Jessica Magne, Editorial Coordinator 0f Clinical Cardiology and Cardiovascular Interventions, The review process for the article “The Handling of Anti-aggregants and Anticoagulants in the Oncologic Heart Patient Submitted to Surgery” was extremely rigorous and detailed. From the initial submission to the final acceptance, the editorial team at the “Journal of Clinical Cardiology and Cardiovascular Interventions” demonstrated a high level of professionalism and dedication. The reviewers provided constructive and detailed feedback, which was essential for improving the quality of our work. Communication was always clear and efficient, ensuring that all our questions were promptly addressed. The quality of the “Journal of Clinical Cardiology and Cardiovascular Interventions” is undeniable. It is a peer-reviewed, open-access publication dedicated exclusively to disseminating high-quality research in the field of clinical cardiology and cardiovascular interventions. The journal's impact factor is currently under evaluation, and it is indexed in reputable databases, which further reinforces its credibility and relevance in the scientific field. I highly recommend this journal to researchers looking for a reputable platform to publish their studies.

img

Dr Marcelo Flavio Gomes Jardim Filho

Dear Editorial Coordinator of the Journal of Nutrition and Food Processing! "I would like to thank the Journal of Nutrition and Food Processing for including and publishing my article. The peer review process was very quick, movement and precise. The Editorial Board has done an extremely conscientious job with much help, valuable comments and advices. I find the journal very valuable from a professional point of view, thank you very much for allowing me to be part of it and I would like to participate in the future!”

img

Zsuzsanna Bene

Dealing with The Journal of Neurology and Neurological Surgery was very smooth and comprehensive. The office staff took time to address my needs and the response from editors and the office was prompt and fair. I certainly hope to publish with this journal again.Their professionalism is apparent and more than satisfactory. Susan Weiner

img

Dr Susan Weiner

My Testimonial Covering as fellowing: Lin-Show Chin. The peer reviewers process is quick and effective, the supports from editorial office is excellent, the quality of journal is high. I would like to collabroate with Internatioanl journal of Clinical Case Reports and Reviews.

img

Lin-Show Chin

My experience publishing in Psychology and Mental Health Care was exceptional. The peer review process was rigorous and constructive, with reviewers providing valuable insights that helped enhance the quality of our work. The editorial team was highly supportive and responsive, making the submission process smooth and efficient. The journal's commitment to high standards and academic rigor makes it a respected platform for quality research. I am grateful for the opportunity to publish in such a reputable journal.

img

Sonila Qirko

My experience publishing in International Journal of Clinical Case Reports and Reviews was exceptional. I Come forth to Provide a Testimonial Covering the Peer Review Process and the editorial office for the Professional and Impartial Evaluation of the Manuscript.

img

Luiz Sellmann