Abstract

Mesenchymal stromal cells (MSC) are a population of non-hematopoietic progenitors native to the bone marrow that are amenable to genetic engineering, making them attractive delivery vehicles for the in vivo production of therapeutic proteins, such as erythropoietin (Epo). We have previously demonstrated that MSC engineered to secrete Epo can be used for the long-term correction of renal failure-induced anemia [Eliopoulos et al.,

J Am Soc Nephrol
.
June 2006
]. However, limited long-term transplanted cell survival compromises the efficacy of MSC-based gene therapy approaches. The current study provides evidence that co-implantation of MSC overexpressing Insulin-like growth factor-1 (IGF-I) improves MSC-based gene therapy of anemia by providing paracrine support to Epo-secreting MSC within a synthetic subcutaneous organoid. The IGF-I receptor was found to be expressed in murine MSC by RT-PCR, and protein expression was confirmed by immunoblot. We also demonstrated MSC MAPK pathway responsiveness to IGF-I stimulation in vitro and subsequent improvement of MSC survival following staurosporin-induced apoptosis. Murine MSC were transduced to overexpress either Epo or IGF-I (hereafter MSC-Epo and MSC-IGF) using retroviral vectors. MSC-Epo were subsequently admixed in a collagen matrix and implanted by subcutaneous injection in both naìˆve mice and a murine model of chronic renal failure, in combination with either MSC-IGF or null MSC. Mice receiving MSC-Epo in conjunction with MSC-IGF experienced a greater and significantly sustained elevation in hematocrit compared to control mice. In addition, mice co-implanted with MSC-IGF and MSC-Epo demonstrated a significant improvement in cardiac function compared to controls. In conclusion, cell-based gene therapy using co-implanted MSC-IGF represents a promising new strategy for the treatment of renal failure-induced anemia, as well as for the improvement of gene-enhanced MSC survival within implanted matrices.

Author notes

Disclosure: No relevant conflicts of interest to declare.