Human Umbilical Cord Perivascular Cells Improve Rat Hepatocyte Function Ex Vivo

Abstract

Hepatocyte functionality and survival decrease rapidly in culture, and both can be improved using bone marrow-derived mesenchymal stromal cells (MSCs). We have previously described an alternative, more plentiful source of MSCs coming from the perivascular area of the umbilical cord, human umbilical cord perivascular cells (HUCPVCs). Our objective was therefore to ascertain whether HUCPVCs could serve as hepatocyte stromal cells ex vivo. For this purpose, rat hepatocytes were cocultured in contact with HUCPVCs (contact coculture). Also, HUCPVCs were cocultured separated from hepatocytes with a semipermeable membrane (noncontact coculture) to assess soluble factor interactions. Next, an HUCPVC-conditioned medium (CM) was used to investigate the possibility of HUCPVC-free support, while flash-frozen HUCPVCs were employed to investigate the effects of nonsoluble interactions. In all experiments, medium samples were taken daily to assess the production of albumin. Also, at certain days, the levels of cytochrome P450 (CYP) activity and urea secretion were tested. RNA extraction was performed at the end of experiments. Our results show that HUCPVCs in contact and noncontact cocultures with hepatocytes improve albumin gene expression and secretion compared to monoculture. Flash-frozen HUCPVCs had a late improvement in albumin secretion, while CM improved it for a short period. Ureagenesis maintenance was improved by contact coculture and flash-frozen HUCPVCs. CYP activity was significantly increased in the presence of flash-frozen HUCPVCs and in noncontact cocultures. We conclude that HUCPVCs can act as stromal cells for rat hepatocytes, and that soluble and nonsoluble factors induce differential effects on hepatocytes.