Challenges and Advances in Magnetic Nanoparticle-Guided Delivery of Cultured Human Corneal Endothelial Cells—A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments for author File: Comments.pdf

Author Response

Comments: 

 

 I read with great interest the manuscript you sent. 

As a topic, it is very topical and presented according to academic requirements. 

The introduction is comprehensive, with sufficient and up-to-date bibliographical references. 

Next, the most relevant subchapters are presented, gathered from the most recent publications in the field on the subject. 

The discussions are extensive and very clear. 

Similarly, the conclusions are brief, concise and to the point. 

What I recommend the authors to do is to proofread and arrange the bibliographical references according to the requirements of the journal. 

 

Response: 

Thank you for your thoughtful and encouraging feedback on our manuscript. We are delighted to hear that you found the topic timely and the presentation in line with academic standards. Your positive remarks on our introduction, subchapters, discussions, and conclusions are much appreciated.

We have carefully proofread and formatted the bibliographical references to meet the journal's requirements, as per your recommendation.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript presented here by Vilkelyte et al., provides an in-depth exploration of the use of magnetic nanoparticles (MNPs) for corneal endothelium replacement. It meticulously reviews current research and clinical trials, assessing the effectiveness and safety of MNPs in ocular applications. The paper highlights various properties of MNPs that make them suitable for such therapies, including their magnetic responsiveness and biocompatibility, while also considering their potential toxicity and impact on ocular health.

The review is well structured and provides a nice overview regarding the state-of-the art in MNPs usage for corneal endothelium replacement and refers to relevant scientific manuscripts and currently on-going clinical trials. However, there are several aspects that, if addressed, could significantly bolster the robustness and impact of the findings.

Review Comments

·         The manuscript provides a comprehensive review of the usage of magnetic nanoparticles (MNPs) for corneal endothelium replacement. However, it would significantly benefit from a detailed comparative analysis between nanoparticles (typically around 50 nm in size) and microparticles (typically around 4 μm). Such a comparison should highlight the advantages of nanoparticles, including less toxicity, enhanced cellular uptake, better clearance, reduced long-term intraocular iron deposition, and lower reactive oxygen species (ROS) generation. Adding this comparison would not only enrich the discussion but also provide clearer guidance for future research directions. References such as DOI: 10.1371/journal.pone.0017452 can be used to support these statements.

 

·         The manuscript currently omits a discussion on the potential effects of magnetic hyperthermia associated with the use of MNPs. This is a critical oversight given the sensitivity of ocular tissues to temperature changes. An exploration of how magnetic hyperthermia could affect cell viability and integration within the corneal endothelium would add depth to the review and offer a more balanced perspective on the safety and feasibility of MNPs in clinical applications.

 

·         While the manuscript touches on the general biocompatibility of MNPs, there is a lack of discussion regarding the generation of ROS following MNPs cellular uptake and its potential impact on sensitive neighboring tissues such as the lens and retina. Considering the high susceptibility of these tissues to oxidative stress, it would be pertinent to discuss whether the use of MNPs increases the risk of conditions like cataracts or retinal/macular degeneration. This discussion could be strengthened by examining current literature on oxidative stress responses in ocular tissues related to nanoparticle exposure.

 

 

Author Response

Thank you very much for your constructive feedback. We sincerely appreciate your insightful comments and suggestions, which have been invaluable in helping us improve our manuscript. We hope you find the amendments we made satisfactory and that they enhance the quality and comprehensiveness of our work.

Comment 1- The manuscript provides a comprehensive review of the usage of magnetic nanoparticles (MNPs) for corneal endothelium replacement. However, it would significantly benefit from a detailed comparative analysis between nanoparticles (typically around 50 nm in size) and microparticles (typically around 4 μm). Such a comparison should highlight the advantages of nanoparticles, including less toxicity, enhanced cellular uptake, better clearance, reduced long-term intraocular iron deposition, and lower reactive oxygen species (ROS) generation. Adding this comparison would not only enrich the discussion but also provide clearer guidance for future research directions. References such as DOI: 10.1371/journal.pone.0017452 can be used to support these statements.

Response 1: Thank you. We acknowledge the importance of comparing MNPs and microparticles in the context of corneal endothelium replacement. We have included a detailed comparative analysis (lines 116-122) highlighting the advantages of MNPs over microparticles in terms of toxicity, cellular uptake etc.

Comment 2: The manuscript currently omits a discussion on the potential effects of magnetic hyperthermia associated with the use of MNPs. This is a critical oversight given the sensitivity of ocular tissues to temperature changes. An exploration of how magnetic hyperthermia could affect cell viability and integration within the corneal endothelium would add depth to the review and offer a more balanced perspective on the safety and feasibility of MNPs in clinical applications.

Response 2: Thank you for your feedback. We have integrated a discussion (lines 430- 446) on the potential effects of magnetic hyperthermia linked to MNPs. This addition explores how magnetic hyperthermia could influence cell viability and its implications for integrating MNPs into the corneal endothelium, aiming to enrich the review with insights into the safety and practicality of MNPs in clinical settings.

Comment 3: While the manuscript touches on the general biocompatibility of MNPs, there is a lack of discussion regarding the generation of ROS following MNPs cellular uptake and its potential impact on sensitive neighbouring tissues such as the lens and retina. Considering the high susceptibility of these tissues to oxidative stress, it would be pertinent to discuss whether the use of MNPs increases the risk of conditions like cataracts or retinal/macular degeneration. This discussion could be strengthened by examining current literature on oxidative stress responses in ocular tissues related to nanoparticle exposure.

Response 3: We appreciate your suggestion to further discuss the generation of ROS following cellular uptake of MNPs and its potential implications for sensitive ocular tissues such as the lens and retina. In our revised manuscript, we have expanded the discussion on this topic (lines 457-478), considering the high susceptibility of these tissues to oxidative stress. We have reviewed current literature on oxidative stress responses in ocular tissues related to nanoparticle exposure to provide a comprehensive analysis.

Reviewer 3 Report

Comments and Suggestions for Authors

In this review, Vilkelyte et al have made a significant effort to review the recent development of magnetic nanoparticle based delivery of corneal endothelial cells to treat corneal endothelial diseases. Although the topic is scientifically interesting and timely, but there are major concerns that should be addressed by the authors to make this review informative to the readers.

1. The title is misleading, magnetic nanoparticle based delivery of corneal endothelial cells is far from being an alternative therapy to endothelial keratoplasty. It is still in its infancy and the phase I human clinical trial is yet to deliver any positive treatment result. So, authors should soften down the title tone. Moreover, this study is a review and not exactly literature review.

2. In the introduction, authors got diverted from the topic, the culturing of CEC seems off-track. It should provide more background regarding nanoparticles and its use in other disease therapy.

3. In section 1.2 “options for delivery of cultured CECs” should describe each delivery methods in details.

4. This is a review so it’s not clear why the authors have added a discussion section (line171) separately.

5. Magnetic nanotechnology section 2.1 is insufficient in addressing the concept of magnetic nanotechnology.

6. The section 2.2 “effectiveness of magnetic nanoparticles in enhanced delivery of HCECs”, authors have summarized the results of Moysidis et al, Xia et al, Mimura et al, Zhao et al. Authors should instead rewrite this section in a more perspective and how these studies can address corneal endothelial cell delivery. This section is should be the major focus of this review and currently it lacks the depth and perspectives.

7. Why there is a separate section for cell viability is not very clear as this can be shortened to paragraph describing the limitations of magnetic nanoparticles based therapy.

8. Authors should provide a table with corneal endothelial diseases and the current available treatments. Also a table indicating the currently used magnetic nanoparticle based cell therapy for different human diseases might be helpful.

9. Authors should provide enough background for endothelial keratoplasty which is currently lacking in the review. Authors should carefully restructure the review to make it scientifically interesting to the readers.

Comments on the Quality of English Language

English is fine. No major issues.

Author Response

Thank you for your constructive feedback on our review. Your suggestions have been incredibly helpful in refining the manuscript on magnetic nanoparticle-based delivery of corneal endothelial cells. We have carefully considered your insights and integrated them into our revisions to enhance the clarity and focus of the paper.

Comment 1: The title is misleading, magnetic nanoparticle based delivery of corneal endothelial cells is far from being an alternative therapy to endothelial keratoplasty. It is still in its infancy and the phase I human clinical trial is yet to deliver any positive treatment result. So, authors should soften down the title tone. Moreover, this study is a review and not exactly literature review.

Response 1: We agree that accurately reflecting the current stage of research is crucial. We have adjusted the title to 'Challenges and Advances in Magnetic Nanoparticle-Guided Delivery of Cultured Human Corneal Endothelial Cells - A Review' to better convey the nature of our study.

Comment 2: In the introduction, authors got diverted from the topic, the culturing of CEC seems off-track. It should provide more background regarding nanoparticles and its use in other disease therapy.

Response 2: Based on your suggestion, we have revised the section and made it appear first after the introduction (line 100) to provide a more focused and comprehensive background on magnetic nanotechnology and its applications in disease therapy. The discussion on culturing corneal endothelial cells (CECs) (line 140) has been significantly shortened to maintain relevance while highlighting the key challenges pertinent to our study.

Comment 3: In section 1.2 “options for delivery of cultured CECs” should describe each delivery methods in details.

Response 3: We completely agree with this comment, section “options for delivery of cultured CECs” has been expanded in greater detail (lines 161-179), offering a more comprehensive overview of the two techniques.

Comment 4: This is a review so it’s not clear why the authors have added a discussion section (line171) separately.

Response 4: According to the "Instructions for Authors" of the Applied Sciences Journal, under the "Reviews" section, it specifies that the structure can include an Abstract, Keywords, Introduction, Relevant Sections, Discussion, Conclusions, and Future Directions. We propose that separating introductory information—such as explaining nanoparticles, detailing the cultivation of corneal endothelial cells, and describing their transplantation—from the main discussion on the effectiveness of magnetic nanoparticles and the challenges associated with their use would enhance the organisation of the paper. While we are open to omitting the discussion (Section 2), doing so would likely necessitate integrating the other sections as subsections within the introduction (Section 1).

Comment 5: Magnetic nanotechnology section 2.1 is insufficient in addressing the concept of magnetic nanotechnology.

Response 5: The section “Magnetic Nanotechnology” has been expanded as discussed in point 2.

Comment 6: The section 2.2 “effectiveness of magnetic nanoparticles in enhanced delivery of HCECs”, authors have summarized the results of Moysidis et al, Xia et al, Mimura et al, Zhao et al. Authors should instead rewrite this section in a more perspective and how these studies can address corneal endothelial cell delivery. This section is should be the major focus of this review and currently it lacks the depth and perspectives.

Response 6: Thank you for your feedback. We have carefully revised now Section 2.1 titled "Effectiveness of Magnetic Nanoparticles in Enhanced Delivery of HCECs" to provide a more in-depth perspective on how these studies contribute to addressing corneal endothelial cell delivery (lines 236-370). The section now emphasises the scientific advancements and potential implications of using magnetic nanoparticles to enhance the delivery and integration of HCECs. Whilst we have done our best to add more perspective and depth, we would also like to note that the diversity in methodologies across studies—encompassing the origin of CECs, animal models, types of magnets, injury models, culture mediums, and negative controls—impedes the generalisability of the findings, making it more difficult to add perspective without listing the various different study findings. We hope you find the revised version to your liking and if not, we would be happy to make further changes.

Comment 7: Why there is a separate section for cell viability is not very clear as this can be shortened to paragraph describing the limitations of magnetic nanoparticles based therapy.

Response 7: The cell-viability section has been shortened and combined with the “Safety and challenges” section and re-named to “Limitations, safety and challenges” (lines 371-493).

Comment 8: Authors should provide a table with corneal endothelial diseases and the current available treatments. Also, a table indicating the currently used magnetic nanoparticle based cell therapy for different human diseases might be helpful.

Response 8: A table providing an overview of current treatments for corneal endothelial diseases has been created (lines 94-97). However, a table detailing the use of magnetic nanoparticle-based cell therapies for different human diseases has not been included, primarily because these therapies are not standardised globally. Instead, these therapies are discussed in the "Magnetic Nanotechnology" section.

Comment 9: Authors should provide enough background for endothelial keratoplasty which is currently lacking in the review. Authors should carefully restructure the review to make it scientifically interesting to the readers.

Response 9: We have included more comprehensive background information on endothelial keratoplasty (lines 71-85). We have carefully restructured the review to ensure it is scientifically engaging for readers. The revisions aim to enhance the clarity and interest of the manuscript, focusing on conveying the scientific aspects of the topic effectively. We worked very hard on this paper and really hope that the revisions help you see it deserves to be published. We appreciate your feedback, which has helped improve the overall quality of the review.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Authors effort to improve the manuscript is commendable. Authors have addressed all the previous concerns and have improved the manuscript significantly. The table 1 will be very helpful to the readers. The revised section for MNPs is very comprehensive and informative. I also agree with the authors argument to keep the discussion section does makes sense here. 

I understand that due to the heterogeneity of MNP based cell therapies it is difficult to provide a table. But it will be helpful if they can add a small comparative table for the three key MNP based therapy references that authors have discussed in this manuscript; Moysidis et al, Xia et al and Zhao et al. This will increase the clarity of the current MNP treatment similarity and differences.

Author Response

  Dear Reviewer,

Thank you for your positive feedback and for recognising our efforts to improve the manuscript. We appreciate your commendation on addressing the previous concerns and the enhancements made. We are glad to hear that you find Table 1 helpful for the readers, and that the revised section on MNPs is comprehensive and informative.

We acknowledge your suggestion regarding the heterogeneity of MNP-based cell therapies and agree that a comparative table summarising the key MNP-based therapy references (Moysidis et al., Xia et al., and Zhao et al.) would be beneficial for clarity.

In response to your suggestion, we have added a new table (Table 2) to the manuscript, which provides a comparative overview of the three key references. This table highlights the MNPs used, experimental models, delivery efficiency, histological findings, key findings, and identified challenges for each study. We believe this addition will enhance the readers' understanding of the similarities and differences among the current MNP treatments discussed in the manuscript.

Thank you once again for your valuable feedback and guidance in improving our work.