Immunomodulatory and regenerative effects of mesenchymal stem cells on allografts

Kenyon, Norma

Abstract

Our goal is to identify a safe and optimally effective mesenchymal stem cell (MSC)-based co-transplant protocol that can be tested in the clinical setting to improve long-term islet and renal allograft survival and function. We will utilize cynomolgus monkey models of cellular (Project 1) and solid organ (Project 2) allotransplantation, in conjunction with genomics and proteomics to define MSC product release criteria and potential biomarkers (Core B), as well as sophisticated tools for data analysis (Core C), to undertake the following.
Aim 1 : Utilize an intrahepatic islet/ MSC co-transplant model to identify the optimal source of the MSC product, i.e. recipient or third party, by determining how MSC origin impacts islet allograft outcome and to assess the efficacy of third party activated MSC (aMSC) in allogeneic renal transplantation.
Aim 2. Determine if intravenous administration of the optimal MSC product can reproducibly lead to reversal of islet allograft rejection and subsequent maintenance of or improvement in islet function and to define the effect of aMSC third party MSC on ischemia reperfusion injury.
Aim 3. Analyze the proteomic, genomic and phenotypic changes that occur in the peripheral blood and tissues of monkey recipients of islet or renal/MSC co-transplants to define biomarkers common to MSC efficacy/non-efficacy for both models, as well as markers unique to each transplant type.
Aim 4. Undertake transplants with the optimal MSC source, coupled with prospective monitoring of potential biomarkers, in order to enable pilot clinical trials of islet or renal/MSC co-transplantation.
These aims will be addressed in a coordinated effort with 2 Projects supported by 3 Cores: Project 1: Mesenchymal stem cell enhancement of islet engraftment and long term survival, University of Miami, PI: Norma S. Kenyon, PhD and Project 2: Mesenchymal stem cell enhancement of organ allograft repair and long term survival, University of Illinois at Chicago, PI: Amelia Bartholomew, MD. The three supporting cores will be: Core A: Administrative Core, University of Miami, PI: Norma S. Kenyon, PhD;Core B: Genomics and Proteomics Core, Scripps Research Institute, La Jolla, PI: Daniel Salomon, MD;and Core C: Supercomputing and Multidimensional Data Analysis Core, University of Illinois at Urbana-Champaign, PI: Peter Bajcsy, PhD. This team will provide a powerful mechanism for data mining and analysis, thereby resulting in acceleration of the discovery process, as compared to the outcome of a single PI working to put together genomic and proteomic data in the context of complex clinical, immunologic and metabolic outcomes.

Public Health Relevance

At present, the potential benefit of the clinical administration of MSC on vascularized and non-vascularized allografts is not known. Upon completion of the proposed studies we hope to develop uniform MSC product release criteria based on discrete and reproducible genomic and proteomic markers. We will know if activation of MSC overcomes variability among donors related to MHC type and immunomodulatory/regenerative properties, thereby enhancing the potential for uniform efficacy in vivo. Project Leader: KENYON, N Project 1: Mesenchymal Stem Cell Enhancement of Islet Engraftment and Long-Term Survival (Description as provided by applicant): We have observed significant enhancement of islet engraftment, prolongation of islet allograft survival and reversal of rejection in cynomolgus monkey recipients of intrahepatic islet/MSC cotransplants. Our goal is to identify a safe and optimally effective transplant protocol that can be tested in the clinical setting to improve long-term islet allograft survival and function. MSC are being utilized experimentally and clinically to mediate inflammation and immunity in a variety of settings;however, the impact of MSC MHC in relation to the recipient and to the cellular or solid organ donor on transplant outcomes has not been defined. In the setting of islet allotransplantation, MHC matching is not taken into consideration when pairing a donor with a recipient. As MSC expansion and banking can take up to 6 weeks, it would be impractical in the clinical setting to utilize MSC from the islet donor. The alternatives are recipient MSC, which would require bone marrow aspiration and MSC expansion/banking while the recipient is on the waiting list, or MSC from a third party. The effect of MHC on islet/MSC transplant outcomes will be studied in Aim 1: To utilize a cynomolgus monkey, intrahepatic islet/MSC co-transplant model to identify the optimal source of the MSC product, i.e., recipient or third-party, by determining how MSC origin impacts islet allograft outcome. Our preliminary data suggests that IV administration of additional MSC at the time of islet allograft destabilization allows for reversal of rejection and, ultimately, enhancement of graft function. This will be assessed in Aim 2: To determine if intravenous administration of the optimal MSC product can reproducibly lead to reversal of islet allograft rejection and subsequent maintenance of or improvement in islet function. Based on published data regarding the mechanisms responsible for the immunomodulatory effect of MSC, as well as on our own preliminary data (Projects 1 and 2), we hypothesize that transplantation of MSC into the liver with islets, as well as infusion of IV MSC post-transplant will result in the induction of T regulatory cells, recruitment of regulatory monocytes/macrophages and endothelial precursors to sites of inflammation (i.e., the graft site) and migration of MSC to lymph nodes draining the graft site. We will undertake studies to address this in Aim 3: To define predictive biomarkers of MSC efficacy and non-efficacy in renal and islet allograft responses. Finally, the data from Projects 1 and 2 and Cores B and C will be incorporated in Aim 4: To undertake transplants with the optimal MSC source, dose and timing of administration, coupled with prospective monitoring of potential biomarkers, in order to enable a pilot clinical trial of islet/MSC cotransplantation.

Public Health Relevance

Islet cell transplantation reverses hyperglycemia and normalizes metabolic control. However, broader application to the cure of type 1 diabetes has been limited by the requirement for chronic immunosuppression and the scarcity of organ donors. MSC delivery with the islets may limit inflammation, enhance islet revascularization and reduce the number of donors needed to achieve insulin independence. Furthermore, MSC administration may constitute a safe and effective way to reverse rejection episodes.