Neonatal Desensitization Supports Long-Term Survival and Functional Integration of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells in Rat Joint Cartilage Without Immunosuppression

Abstract

Immunological response hampers the investigation of human embryonic stem cells (hESCs) or their derivates for tissue regeneration in vivo. Immunosuppression is often used after surgery, but exhibits side effects of significant weight loss and allows only short-term observation. The purpose of this study was to investigate whether neonatal desensitization supports relative long-term survival of hESC-derived mesenchymal stem cells (hESCMSCs) and promotes cartilage regeneration. hESC-MSCs were injected on the day of birth in rats. Six weeks after neonatal injection, a full-thickness cylindrical cartilage defect was created and transplanted with a hESC-MSCseeded collagen bilayer scaffold (group d + s + c) or a collagen bilayer scaffold (group d + s). Rats without neonatal injection were transplanted with the hESC-MSC-seeded collagen bilayer scaffold to serve as controls (group s + c). Cartilage regeneration was evaluated by histological analysis, immunohistochemical staining, and biomechanical test. The role of hESC-MSCs in cartilage regeneration was analyzed by CD4 immunostaining, cell death detection, and visualization of human cells in regenerated tissues. hESC-MSCs expressed CD105, CD73, CD90, CD29, and CD44, but not CD45 and CD34, and possessed trilineage differentiation potential. Group d + s + c exhibited greater International Cartilage Repair Society (ICRS) scores than group d + s or group s + c. Abundant collagen type II and improved mechanical properties were detected in group d + s + c. There were less CD4 + inflammatory cell infiltration and cell death at week 1, and hESC-MSCs were found to survive as long as 8 weeks after transplantation in group d + s + c. Our study suggests that neonatal desensitization before transplantation may be an efficient way to develop a powerful tool for preclinical study of human cell-based therapies in animal models.

Neonatal immune-tolerance in mice does not prevent xenograft rejection

“…Neonatal desensitization is a new strategy for long-term immune protection of human neural cells transplanted into the adult brain, without the need for immunosuppression (Kelly et al, 2009; Peiguo et al, 2012; Zhang et al, 2013). Rodents are given intraperitoneal (i.p.)…”

Generating Cartilage Repair from Pluripotent Stem Cells

“…125 hESC-MSC-seeded bilayer collagen scaffolds also showed the ability to generate cartilage in the patella groove defect area of rats. 126 Chondrogenesis from hESCs in perfusion bioreactors using porous silk scaffolds 127 and on nanoscale electrospun fibres has also been reported. 128 In general, none of these approaches has yielded flawless repair from hESC-derived chondrocytes and further research is needed, but the hydrogel studies, in particular, produce some quality hyaline, rather than fibrous cartilage in vivo, suggesting a way forward to clinical application.…”

Neonatal Desensitization for the Study of Regenerative Medicine

“…For example, rat hosts with induced knee cartilage defects were successfully desensitized with 1 × 10 5 hESC-derived mesenchymal stem cells (hESC-MSC) [45]. These hosts could support survival of a collagen bilayer scaffold seeded with hESC-MSC for at least 8 weeks post-transplantation, whereas animals that were not desensitized neonatally showed increased T-cell infiltration and transplant rejection [45].…”

“…For example, rat hosts with induced knee cartilage defects were successfully desensitized with 1 × 10 5 hESC-derived mesenchymal stem cells (hESC-MSC) [45]. These hosts could support survival of a collagen bilayer scaffold seeded with hESC-MSC for at least 8 weeks post-transplantation, whereas animals that were not desensitized neonatally showed increased T-cell infiltration and transplant rejection [45]. Another group aimed to determine whether human Müller glia stem cells have the potential to differentiate into retinal ganglion cells (RGC) when transplanted into an LH rat model of RGC depletion [46].…”

“…It allows xenograft survival to a comparable extent to conventional immunosuppressant drugs, but for substantially longer [15,[45][46][47]. Desensitization of rat hosts will therefore permit long-term studies of graft maturation and functional outcomes that have not previously been possible.…”