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Evaluating the Effects of Brain Death Physiology and Immunosuppression on the Muscle-Derived Stem Cell Niche in a Large Animal Transplant Model

Mohamed Awad MD1, Anil Chaturvedi MS1, Samuel Boas BS1, Arvin Smith BS1, James Reynolds PhD2, Anand Kumar MD1
1 University Hospitals, Department of Plastic Surgery, Cleveland, OH 2 Case Western Reserve Univers
2020-02-12

Presenter: Mohamed Awad

Affidavit:
Mohamed Awad

Director Name: Mohamed Awad

Author Category: Resident Plastic Surgery
Presentation Category: Basic Science Research
Abstract Category: General Reconstruction

Background: Muscle-derived stem cells (MDSCs) are robust mediators of tissue regeneration and mixed chimerism in small animal murine transplant models.We hypothesize that BD negatively affect the MDSC stem cell-niche in vascularized composite allografts (VCA) and may affect tolerance/rejection. Our study aim was to evaluate the viability, quantity, and stem cell differentiation of MDSCs under various conditions in a porcine VCA model.
Methods: MDSCs were harvested in 1) pre BD donor, 2) post BD donor, 3) Immunosuppressed transplanted donor VCA, and from 4) Immunosuppressed recipient muscle. Samples were then harvested throughout. MDSC populations were isolated and imaged at various time points (t=0-10 days). MDSCs we then seeded in 6 well plates for differentiation assays over 21 days.
Results: Percent confluence at t=10 days was (81%, 39%, 71%,55% group 1-4 respectively (p < 0.01) in all group compared with pre BD with the greatest expansion and post PD with the lowest. Flow-cytometry demonstrated significantly higher population of PERCP, CFS, APC markers pre-brain death 27%,43%,61% vs post-brain death 7%, 14%, 12% (P=0.001). Osteogenesis, chondrogenesis, adipogenesis was maintained pre brain death but with significantly increased differentiation with later preplates and in all differentiation assay types 2 vs. 4 vs. 6 Osteo (27% vs. 61% 74% 61%) (p<0.01), Chrondo (3% vs. 21%, 13% ,27%)(p<0.01), and Adipo (9% vs. 23%,18%,23%)(p=0.04)
Conclusion: Brain-death and immunosuppression each individually impair MDSC niche expansion and mitosis based on time to confluence. Successful transplantation ameliorated the negative effects of immunosuppression by enhancing cell division by removal of BD physiology.

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