Adipose-derived stromal cells (ASCs) are often referred to as adipose-derived stem cells due to their potential to undergo multilineage differentiation. Their promising role in tissue engineering and ability to modulate the immune system are the focus of extensive research. A number of clinical trials using ASCs are currently underway to better understand the role of such cell niche in enhancing or suppressing the immune response. If governable, such immunoregulatory role would find application in several conditions in which an immune response is present (i.e., autoimmune conditions) or feared (i.e., solid organ or reconstructive transplantation). Although allogeneic ASCs have been shown to prevent acute GvHD in both preclinical and clinical studies, their potential warrants further investigation. Well-designed and standardized clinical trials are necessary to prove the role of ASCs in the treatment of immune disorders or prevention of tissue rejection. In this paper we analyze the current literature on the role of ASCs in immunomodulation in vitro and in vivo and discuss their potential in regulating the immune system in the context of transplantation.

Background aims Donor-derived vertebral bone marrow (BM) has been proposed to promote chimerism in solid organ transplantation with cadaveric organs. Reports of successful weaning from immunosuppression in patients receiving directed donor transplants in combination with donor BM or blood cells and novel peri-transplant immunosuppression has renewed interest in implementing similar protocols with cadaveric organs. Methods We performed six pre-clinical full-scale separations to adapt vertebral BM preparations to a good manufacturing practice (GMP) environment. Vertebral bodies L4–T8 were transported to a class 10 000 clean room, cleaned of soft tissue, divided and crushed in a prototype bone grinder. Bone fragments were irrigated with medium containing saline, albumin, DNAse and gentamicin, and strained through stainless steel sieves. Additional cells were eluted after two rounds of agitation using a prototype BM tumbler. Results The majority of recovered cells (70.9 ± 14.1%, mean ± SD) were eluted directly from the crushed bone, whereas 22.3% and 5.9% were eluted after the first and second rounds of tumbling, respectively. Cells were pooled and filtered (500, 200 μm) using a BM collection kit. Larger lumbar vertebrae yielded about 1.6 times the cells of thoracic vertebrae. The average product yielded 5.2 ± 1.2×1010 total cells, 6.2 ± 2.2×108 of which were CD45+ CD34+. Viability was 96.6 ± 1.9% and 99.1 ± 0.8%, respectively. Multicolor flow cytometry revealed distinct populations of CD34+ CD90+ CD117 dim hematopoietic stem cells (15.5 ± 7.5% of the CD34 + cells) and CD45− CD73+ CD105+ mesenchymal stromal cells (0.04 ± 0.04% of the total cells). Conclusions This procedure can be used to prepare clinical-grade cells suitable for use in human allotransplantation in a GMP environment.

Acute skin rejection in vascularized composite allotransplantation (VCA) is the major obstacle for wider adoption in clinical practice. This study utilized computational modeling to identify biomarkers for diagnosis and targets for treatment of skin rejection. Protein levels of 14 inflammatory mediators in skin and muscle biopsies from syngeneic grafts [n = 10], allogeneic transplants without immunosuppression [n = 10] and allografts treated with tacrolimus [n = 10] were assessed by multiplexed analysis technology. Hierarchical Clustering Analysis, Principal Component Analysis, Random Forest Classification and Multinomial Logistic Regression models were used to segregate experimental groups. Based on Random Forest Classification, Multinomial Logistic Regression and Hierarchical Clustering Analysis models, IL-4, TNF-α and IL-12p70 were the best predictors of skin rejection and identified rejection well in advance of histopathological alterations. TNF-α and IL-12p70 were the best predictors of muscle rejection and also preceded histopathological alterations. Principal Component Analysis identified IL-1α, IL-18, IL-1β, and IL-4 as principal drivers of transplant rejection. Thus, inflammatory patterns associated with rejection are specific for the individual tissue and may be superior for early detection and targeted treatment of rejection.