Structural and Functional Characterization of Deceased Donor Stem Cells: A Viable Alternative to Living Donor Stem Cells

Apheresis of Deceased Donors as a New Source of Mobilized Peripheral Blood Hematopoietic Stem Cells for Transplant Tolerance

BACKGROUND

Solid organ transplantation is the therapy of choice for many patients with end-stage organ failure; however, recipients must remain on lifelong immunosuppression, leaving them susceptible to infections and cancer. The study of transplant tolerance to prolong graft survival in the absence of immunosuppression has been restricted to recipients of living donor allografts; however, deceased donors significantly outnumber living donors. Mobilization of hematopoietic stem cells (HSCs) from the bone marrow to peripheral blood (PB) could allow PB-HSCs to be used to induce tolerance in deceased donor kidney recipients; however, a major concern is the well-known concomitant mobilization of immune cells into the liver.

METHODS

We mobilized HSCs to the PD using a protocol of 2 doses of granulocyte colony-stimulating factor and 1 dose of plerixafor, followed by the collection of mobilized cells via apheresis in 3 deceased donors. The physiological, laboratory, and radiographic parameters were monitored throughout the procedure. Longitudinal biopsies were performed to assess the potential for ectopic liver mobilization.

RESULTS

The use of both agents led to the successful mobilization of peripheral blood CD34+ cells, demonstrating the potential for use in transplant tolerance protocols. Increased immune cell trafficking into the liver was not observed, and apheresis of mobilized cells resulted in a uniform decrease in all liver leukocyte subsets.

CONCLUSIONS

HSCs can be mobilized and collected from the PB of brain-dead donors. This new approach may facilitate the dissemination of immune tolerance trials beyond living-donor kidney transplantation to deceased-donor transplantation, without sacrificing the transplantability of the liver.

Mesenchymal Stem/Stromal Cells in Organ Transplantation

Organ transplantation is essential and crucial for saving and enhancing the lives of individuals suffering from end-stage organ failure. Major challenges in the medical field include the shortage of organ donors, high rates of organ rejection, and long wait times. To address the current limitations and shortcomings, cellular therapy approaches have been developed using mesenchymal stem/stromal cells (MSC). MSC have been isolated from various sources, have the ability to differentiate to important cell lineages, have anti-inflammatory and immunomodulatory properties, allow immunosuppressive drug minimization, and induce immune tolerance towards the transplanted organ. Additionally, rapid advances in the fields of tissue engineering and regenerative medicine have emerged that focus on either generating new organs and organ sources or maximizing the availability of existing organs. This review gives an overview of the various properties of MSC that have enabled its use as a cellular therapy for organ preservation and transplant. We also highlight emerging fields of tissue engineering and regenerative medicine along with their multiple sub-disciplines, underlining recent advances, widespread clinical applications, and potential impact on the future of tissue and organ transplantation.

Differentiation of Human Deceased Donor, Adipose-Derived, Mesenchymal Stem Cells into Functional Beta Cells

There is an emerging need for the rapid generation of functional beta cells that can be used in cell replacement therapy for the treatment of type 1 diabetes (T1D). Differentiation of stem cells into insulin-producing cells provides a promising strategy to restore pancreatic endocrine function. Stem cells can be isolated from various human tissues including adipose tissue (AT). Our study outlines a novel, non-enzymatic process to harvest mesenchymal stem cells (MSC) from research-consented, deceased donor AT. Following their expansion, MSC were characterised morphologically and phenotypically by flow cytometry to establish their use for downstream differentiation studies. MSC were induced to differentiate into insulin-producing beta cells using a step-wise differentiation medium. The differentiation was evaluated by analysing the morphology, dithizone staining, immunocytochemistry, and expression of pancreatic beta cell marker genes. We stimulated the beta cells with different concentrations of glucose and observed a dose-dependent increase in gene expression. In addition, an increase in insulin and c-Peptide secretion as a function of glucose challenge confirmed the functionality of the differentiated beta cells. The differentiation of adipose-derived MSC into beta cells has been well established. However, our data demonstrates, for the first time, that the ready availability and properties of MSC isolated from deceased donor adipose tissue render them well-suited as a source for increased production of functional beta cells. Consequently, these cells can be a promising therapeutic approach for cell replacement therapy to treat patients with T1D.