Conditioning of neonatal pigs using low-dose chemotherapy and murine fetal tissue before murine hybridoma transplantation.

Immunosuppression, myeloablation, and the use of immunologically immature tissue can overcome major histocompatibility complex barriers by inducing tolerance. With the goal of inducing tolerance to BALB/c-derived murine hybridoma cells producing the 4C6 monoclonal antibody (mAb), we transplanted BALB/c fetal tissue into neonatal pigs during a regimen of low-dose conditioning with busulfan and cyclophosphamide. After the tolerance induction phase, animals received intraperitoneal injections of 4C6 mAb hybridoma cells. Evidence of persistence of injected cells over time was sought by molecular analysis of peripheral blood for the presence of mouse genomic sequences and circulating 4C6 mAb. Persistence of donor polymerase chain reaction signal during the entire duration of the study, detectable mAb titer for 6 weeks, and a twofold increase of mAb concentration after a boost hybridoma infusion was observed in one animal receiving six consecutive administrations of the conditioning regimen. Our model has the distinctive advantage of allowing functional monitoring of engrafted cells for studying tolerance induction strategies. In addition, this model could be the basis for approaches aimed at producing mAbs in tolerized large animals.

Target-antigen Detection and Localization of Human Amniotic-derived Cells after in Utero Transplantation in Rats.

Human amniotic-derived cells (hAMCs) have recently raised interest for their differentiation capability and immunomodulatory properties. To assess the feasibility of hAMCs therapeutic treatment during fetal development, we explored the localization of cells derived from the human amniotic membrane in rat organs after in utero transplantation. Rats were sacrificed at different time points and their organs were analyzed for the distribution of hAMCs by immunohistochemistry using an antibody against Human Cytoplasm and through detection of human DNA. Immunohistochemical and PCR analysis showed that most of the rat tissues presented human cells/DNA suggesting a widespread migration of hAMCs after transplantation. We developed an efficient target-antigen detection method based on an immunohistochemical technique that resulted to be highly specific and sensitive to identify the hAMCs into rat tissues.