The Transplantation of Pancreatic Islets to Portal Vein: The Influence on Liver Tissue

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a review which reveals the findings of the liver after islet transplantation. especially liver damage due to intraportal islet transplantation. This point of view of this review is unique and interesting. However, the main point of this review is not obvious and difficult for understanding because each chapter is disconnected and mixed up.

I have some suggestions for improving the quality.

1. Introduction: The main theme of this review is islet transplantation. So, the background, etiology, procedure of transplantation (allo and auto), indication, and or outcome should be described in detail at first. Instead, explanation about diabetes and components of islet cells should be compromised or deleted because they are not correlated with liver findings after islet transplantation.

2. After Introduction, how about including detail explanation about the procedure of intraportal islet transplantation and the complication? Because many readers who are not speciality in islet transplantation hardly understand the reality of intraportal islet transplantation. Furthermore, please discuss to include a scheme of islet transplantation for reader's understanding.

3. The effect of islet transplantation on liver: This chapter should be split to "early influence" and "late influence". Regarding early influence, please describe histological changes of the liver around the transplanted islets. Please discuss including informative histological images of the liver stained for apoptotic cells and inflammatory cells. Explanation about liver tissue (described in Chapter 2) should be combined in the chapter with explanation of histological changes of liver tissue after islet transplantation. Please discuss to include the scheme of early histological changes of the liver after islet transplantation. After that, please discuss that description about late influence including liver steatosis is summarized as a new chapter.

Finally, how about including transplant efficacy of intraportal islet transplantation comparing with other transplant sites using previous animal studies. This data indicates the preferability of intraportal site.

Author Response

General comment: This is a review which reveals the findings of the liver after islet transplantation. especially liver damage due to intraportal islet transplantation. This point of view of this review is unique and interesting. However, the main point of this review is not obvious and difficult for understanding because each chapter is disconnected and mixed up. I have some suggestions for improving the quality.

Response:      Thank you for this point. The absence of the basic idea of the text, briefly expressed at the beginning of the article, is very important and often missing. We have added it. 

Comment 1:   Introduction: The main theme of this review is islet transplantation. So, the background, etiology, procedure of transplantation (allo and auto), indication, and or outcome should be described in detail at first. Instead, explanation about diabetes and components of islet cells should be compromised or deleted because they are not correlated with liver findings after islet transplantation.

Response:      We agree with the reviewer; the main focus should be paid to the islet-liver interaction and its possible side effects. But we feel important to explain the islets interaction with surrounding tissue and the specificity of natural insulin release as a background, which is impaired during isolation and needs to be restored after transfer to recipient. In respect to reviewer recommendations, we have shortened and more focused the general explanation of diabetes and islet components, as well as general indications for this therapeutic approach. The Table 1 was erased as redundant; Table 2 is renamed to Table 1. The text modifications can be seen in lines 30-124.

Comment 2: After Introduction, how about including detail explanation about the procedure of intraportal islet transplantation and the complication? Because many readers who are not speciality in islet transplantation hardly understand the reality of intraportal islet transplantation. Furthermore, please discuss to include a scheme of islet transplantation for reader's understanding.

Response:      The introduction part 1.3. was divided into “1.3. Pancreatic Islet Isolation” and “1.4. Pancreatic Islet Transplantation” sections and the text was expanded in order to include more details in description of the isolation and transplantation procedures (both allo- and auto-), indications, and expected outcomes. With the help of paid version AI Gemini, using the corresponding author prompts the Figure 2A-D was prepared, to explain the isolation and transplantation processes schematically for those, who are not familiar with this method, as was requested by reviewer 1.

 According to outcomes of the islet transplantation, it is pretty complicated and needs extensive explanation, which was not the intended purpose of this text. Therefore, we mentioned some results in general principles and believe, it could be enough with reference to papers summarizing islet transplantation program in extenso. Mentioned above changes can be seen in lines 124 – 202.

The paragraph “2.1. Technical aspects of portal vein islet transplantation” was erased from the section “2. Liver as a preferred site for islet transplantation” and partially used in “1.4. Pancreatic islet transplantation – technical aspects …”

Comment 3: The effect of islet transplantation on liver: This chapter should be split to "early influence" and "late influence". Regarding early influence, please describe histological changes of the liver around the transplanted islets. Please discuss including informative histological images of the liver stained for apoptotic cells and inflammatory cells. Explanation about liver tissue (described in Chapter 2) should be combined in the chapter with explanation of histological changes of liver tissue after islet transplantation. Please discuss to include the scheme of early histological changes of the liver after islet transplantation. After that, please discuss that description about late influence including liver steatosis is summarized as a new chapter.

Response:      Section three was divided into a part focusing on early “3.1. The early interaction of liver with islet grafts” and late interaction “3.2. The delayed interaction of liver with islet grafts” of the graft with liver tissue. At the beginning of this section, we briefly outlined what happens immediately and later after the islets are inserted into the portal vein. This information was discussed in more detail later on. We understand that the initial paragraphs may have been confusing, so we deleted them (lines 324-339) and edited the text to describe both processes in detail. The Figure 5 was added in order to show the histological picture of immediate interaction of islets with portal vein blood. The panel A, HE staining was prepared from the our archive pictures and show the intraportal thrombus attached transplanted islets including lymphocyte infiltration, panels B-D show the apoptotic cells developed in the early post-transplant period including chart indicating changes in time course and are reproduced from the paper of Matsuoka et al. in Scientific reports, which is fully open access (CC-BY licence) allowing free reproduction of Figures – confirmation is attached.

Comment 4: Finally, how about including transplant efficacy of intraportal islet transplantation comparing with other transplant sites using previous animal studies. This data indicates the preferability of intraportal site.

Response:      The detail analysis and comparison of individual sites potentially tested for islet transplantation would be really extensive. This summary was published several times and three papers were referred in the paper (17-19). In respect to reviewer request, we add several sentences at the end of section 1.3. (lines 140-150).

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have presented an interesting manuscript that addresses, describes, and illustrates the importance of pancreatic islet transplantation for the purpose of mitigating diabetes mellitus. The authors focus on describing a primary issue concerning the impact of this approach in relation to the recipient organ: the liver. The authors have done an excellent job both from the bibliographic research and the illustrative point of view. However, we would like to draw the authors' attention to the possibility of introducing some changes that (in our humble opinion) could enhance the manuscript and make it (possibly) more precise and interesting:

Major Comments:

1) Paragraph 1.3 In this section, there is definitely a missing bibliographic entry regarding the procedure for separating pancreatic islets. A mention of Ricordi's chamber must absolutely be included in this part of the manuscript.

2) Figure number 2 should be revised. It would be preferable to include separate immunohistochemistry images showing the staining of insulin and glucagon in the islets of Langerhans. Additionally, it would be more useful to show an electron microscopy photograph depicting the beta cells of the pancreatic islets.

3) In this review, reference 65 discusses the use of 400-micron microcapsules. The authors seem to focus on the issue of portal complications but do not clearly describe the concept of "encapsulation" as it strictly relates to the islets of Langerhans. The authors need to address this section and discuss the issue, also adding some bibliographic references.

4) The authors should mention in this literature review, even briefly, the medical devices and other possibilities available in the medical field as alternatives to pancreatic islet transplantation.

5) The authors should also include a small paragraph regarding pancreas transplantation.

Minor Comments:

1) In accordance with the journal's format, bibliographic citations must be included in square brackets.

Author Response

Comment 1:  Paragraph 1.3 In this section, there is definitely a missing bibliographic entry regarding the procedure for separating pancreatic islets. A mention of Ricordi's chamber must absolutely be included in this part of the manuscript.

Response:      You are right, it is an important information. Thank you for pointing that out. We added a mention of Ricordi’s chamber as well as the picture (Figure 2c) and corresponding reference.

 

Comment 2:  Figure number 2 should be revised. It would be preferable to include separate immunohistochemistry images showing the staining of insulin and glucagon in the islets of Langerhans. Additionally, it would be more useful to show an electron microscopy photograph depicting the beta cells of the pancreatic islets.

Response:      We thank the reviewer for this comment. However, we believe there has been a misunderstanding, and we will try to better explain our intention and what we wanted to show with this image. We intended to highlight the arrangement of alpha and beta cells, which enables paracrine influence between cells. That is why we chose dual staining, which clearly shows the relative positions of the endocrine cells within the islet. Regarding the electron microscopic image of the ultrastructure of beta cells: Opponent No. 1 requests that the description of diabetes and islets be shortened, and that the text focus more on the main issue: the interaction between the graft and liver tissue. In this context, we believe that the ultrastructural image of the beta cell is not necessary. 

Comment 3:  In this review, reference 65 discusses the use of 400-micron microcapsules. The authors seem to focus on the issue of portal complications but do not clearly describe the concept of "encapsulation" as it strictly relates to the islets of Langerhans. The authors need to address this section and discuss the issue, also adding some bibliographic references.

Response:      Thank you for this point. But the islet encapsulation is another large field of transplantation research. Mentioned paper should confirm the temporary influence of any particles on portal vein blood flow. So we do believe, that there is not space enough for reliable discussion of this problem.

Specifically, in referred paper: “these particles are empty polymeric microcapsules (400 μm diameter, alginate-based), not containing pancreatic islets; the study intentionally used empty capsules to assess safety and biocompatibility without confounding biological activity from live cells”.

Comment 4:  The authors should mention in this literature review, even briefly, the medical devices and other possibilities available in the medical field as alternatives to pancreatic islet transplantation.

Response:      Thank you for this point. We explained more the conventional therapeutic approaches (see lines 45-53) and add two references (2, 3)

Comment 5:  The authors should also include a small paragraph regarding pancreas transplantation.  

Response:      Thank you for this point. You are right that pancreas organ transplantation should be mentioned as a substantial and clinically relevant alternative. We mentioned in in lines 59 – 65.

Comment 6: In accordance with the journal’s format, bibliographic citations must be included in square brackets.

Response:      Done in accordance with the journal’s guidelines.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors revised their manuscript following reviewer's comments. 

Regarding Figure 2, please include purification process between digestion (2C) and transplantation (2D).

Author Response

Reviewers’ 1 comment regarding Figure 2
"please include purification process between digestion (2C) and transplantation (2D).", and kindly upload the revised file within 4 days.

Response: Dear reviver, you are right,thank you for this comment. It was done.

Author Response File: Author Response.docx