PONE-D-19-19424

Ex Vivo Perfusion-Based Engraftment of Genetically Engineered Cell Sensors into Transplantable Organs

PLOS ONE

Dear Professor Parekkadan,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The critical concerns are raised on the preservaton of hepatic function after used the cellular biosensor sysytem (considerlly, such as two cuff method might be a pratical way to examine the hepatic function of recipient animal after liver transplantation) , and the comparison of different cell sources, fibroblasts vs mesenchymal stromal cells or mesenchymal stem cells  Please find the following constructive parts of comments of the reviewers.  

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PLOS ONE

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Reviewers' comments:

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Reviewer #1: Yes

Reviewer #2: Partly

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

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Reviewer #1: In the study entitled “Ex Vivo Perfusion-Based Engraftment of Genetically Engineered Cell Sensors into Transplantable Organs”, Parekkadan et al. proves an innovative concept of integrating synthetic reporter cells ex vivo into organs as a transplant-within-a-transplant during functional organ preservation with a vision to use cell biosensors as a broad way to monitor and treat tissue transplants. Overall, this work has a degree of novelty and may be used for clinical application in future. However, I have a few comments as followings:

1. The author concluded that the method of Ex Vivo Perfusion-Based Engraftment in this study could be used for therapeutic application. However, they only tested the feasibility of Ex Vivo Perfusion-Based Engraftment using fibroblast cell model. As far as we know, a body of evidence shows that stem cells can display beneficial therapeutic effects on the rejection of liver transplantation and it is not hard to isolated stem cells from allogeneic sources. Therefore, in this regard I suggest that stem cell model should be tested at least.

2. In fact, the mechanisms underlying the therapeutic effects on the rejection of liver transplantation are not fully elucidated. In many studies stem cells have been reported to function by secreting some key factors and exosomes, so it seems there may be no need for stem cells to dwell or distribute specifically in liver and then display protective effects after liver transplantation. Therefore, I suggest the authors to compare the therapeutic effects of stem cells between traditional injection method and Ex Vivo Perfusion-Based Engraftment method using rat liver transplant model.

Reviewer #2: Parekkadan, et al., present an interesting proof of concept study, wherein they demonstrate the ability of a machine-based perfusion system to distribute transducer fibroblasts, which produce Luciferase, into rat livers as demonstration that a system using in vivo biosensors might someday be used in the solid organ transplant settings to detect clinical events.

The overall concept is innovative and “out of the box.” They demonstrate in this article the ability to take fibroblasts, transduced with lentiviral vectors, and demonstrate that they successfully distribute throughout these organs. However, a number of questions that are relevant to the demonstration of proof of concept and practical ability to stimulate future translation, are worth considering.

First, one critical piece of this is demonstration that the distributed cells do not impair hepatic function. It is not clear to me that the demonstrations here are sufficient. For example, there is minimal edema and AST levels did not rise significantly, but the ideal demonstration of this would have been transplantation of a cellular biosensor-infused liver into an allogeneic (or even syngeneic) recipient with demonstration that the recipient animal can sustain adequate hepatic function.

Second, the choice of fibroblasts (vs., as discussed frequently, mesenchymal stromal cells that have a relatively broad history in clinical transplant settings) might become problematic, with the potential to induce inflammation vs. other cell types. Also the choice of a vector system capable of propagating into daughter cells might raise concerns about inflammatory (or even neoplastic) potential in the real world setting.

All of the above concerns do not undermine the interesting concept, but they raise issues about what level of proof of concept demonstration (e.g., if not sufficient to determine lack of impact on hepatic function and using different cells or vectors than might realistically be used in initial clinical application) has been achieved herein.

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Reviewer #1: No

Reviewer #2: No

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Ex Vivo Perfusion-Based Engraftment of Genetically Engineered Cell Sensors into Transplantable Organs

PONE-D-19-19424R1

Dear Dr. Parekkadan,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

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With kind regards,

Yun-Wen Zheng

Academic Editor

PLOS ONE

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