Engineering human renal epithelial cells for transplantation in regenerative medicine.

Cellular transplantation may treat several human diseases by replacing damaged cells and/or providing a local source of trophic factors promoting regeneration. We utilized human renal epithelial cells (hRECs) isolated from cadaveric donors as a cell model. For efficacious implementation of hRECs for treatment of kidney diseases, we evaluated a novel encapsulation strategy for immunoisolation of hRECs and lentiviral transduction of the Green Fluorescent Protein (GFP) as model gene for genetic engineering of hRECs to secrete desired trophic factors. In specific, we determined whether encapsulation through conformal coating and/or GFP transduction of hRECs allowed preservation of cell viability and of their trophic factor secretion. To that end, we optimized cultures of hRECs and showed that aggregation in three-dimensional spheroids significantly preserved cell viability, proliferation, and trophic factor secretion. We also showed that both wild type and GFP-engineered hRECs could be efficiently encapsulated within conformal hydrogel coatings through our fluid dynamic platform and that this resulted in further improvement of cell viability and trophic factors secretion. Our findings may lay the groundwork for future therapeutics based on transplantation of genetically engineered human primary cells for treatment of diseases affecting kidneys and potentially other tissues.

Minced cartilage without cell culture serves as an effective intraoperative cell source for cartilage repair.

Traumatic articular cartilage injuries heal poorly and may predispose patients to the early onset of osteoarthritis. One current treatment relies on surgical delivery of autologous chondrocytes that are prepared, prior to implantation, through ex vivo cell expansion of cartilage biopsy cells. The requirement for cell expansion, however, is both complex and expensive and has proven to be a major hurdle in achieving a widespread adoption of the treatment. This study presents evidence that autologous chondrocyte implantation can be delivered without requiring ex vivo cell expansion. The proposed improvement relies on mechanical fragmentation of cartilage tissue sufficient to mobilize embedded chondrocytes via increased tissue surface area. Our outgrowth study, which was used to demonstrate chondrocyte migration and growth, indicated that fragmented cartilage tissue is a rich source for chondrocyte redistribution. The chondrocytes outgrown into 3-D scaffolds also formed cartilage-like tissue when implanted in SCID mice. Direct treatment of full-thickness chondral defects in goats using cartilage fragments on a resorbable scaffold produced hyaline-like repair tissue at 6 months. Thus, delivery of chondrocytes in the form of cartilage tissue fragments in conjunction with appropriate polymeric scaffolds provides a novel intraoperative approach for cell-based cartilage repair.

Characterization of platelet-derived growth factor-C (PDGF-C): expression in normal and tumor cells, biological activity and chromosomal localization.

The predicted platelet-derived growth factor-C (PDGF-C) polypeptide contains an N-terminal CUB-like domain and a C-terminal domain with homology to members of the PDGF/vascular endothelial growth factor (VEGF) family. PDGF-C mRNA is widely expressed in normal tissues and does not appear to be up-regulated in the tumor cell lines tested. The PDGF-C gene was mapped to human chromosome 4q31-32. PDGF-C protein and the CUB domain of PDGF-C expressed in Escherichia coli, were able to stimulate proliferation of human artery smooth muscle cells, but were inactive on umbilical vein endothelial cells, osteoblasts, fibroblasts, skeletal muscle cells (SkMC), bovine chondrocytes, and rat myocardium cells. Although the mitogenic activity of PDGF-C and the CUB domain was only observed at concentrations ranging from 1 to 10 microg/ml, substitution of Cys(124) by Ser or deletion of Cys(124) significantly reduced the mitogenic activity. Our data suggest a possible role of the CUB domain of PDGF-C in addition to its role in maintaining latency of the PDGF domain.