The role of small leucine rich proteins osteogenesis of human mesenchymal stem cells

Abstract

Introduction. Small Leucine Rich Proteins (SLRPs) are a family of 17 proteoglycans and glycoproteins found within the extracellular matrix (ECM). The roles of these proteins in osteoblast development have not been explored in human. Problem Statement. This study investigates the gene expression of six members of the SLRP family during osteogenesis in donor matched human subcutaneous adipose tissue-derived stem cells (ADSC) and bone marrow derived stem cells (BMSC). Procedures/Data/Observations. Global gene expression data was collected from two mouse osteoblast cell lines. Donor matched subcutaneous adipose tissue and bone marrow tissue was collected from 5 female patients (mean age 72.8 ± 6.9) during abdominal or orthopaedic surgery. ADSC and BMSC were isolated and differentiated using osteogenic media (OSM). mRNA was extracted at days 0, 7 and 28. Gene expression of SLRPs was analysed using qRT-PCR. Results. Six out of 17 SLRP family members were up-regulated in mouse osteoblasts thus they have been selected. In ADSC, Osteomodulin (OMD) was up-regulated by 26.6-fold at day 7 and 17.9-fold at day 28. In BMSC, higher OMD up-regulation was seen at day 7 (125.4-fold) and a smaller one at day 28 (47.5-fold). Epiphycan (EPYC) was also up-regulated at both time points in both cells (2.6-fold at day 7 and 3.3-fold at day 28 in ADSC; 1.6-fold at day 7 and 5.9-fold at day 28 in BMSC). On the contrary, Lumican (LUM) was down –regulated by 0.6-fold at day 7 and 0.2-fold at day 28 in ADSC; 0.6-fold at day 7 and 0.04-fold at day 28 in BMSC. Other SLRPS were not changed by osteogenic stimulation. Conclusions. Previously unrecognized roles of SLRP members were demonstrated in two human MSC models undergoing osteogenesis. OMD and EPYC are likely to be most involved. Further study on their protein expressions and locations in ECM niche is needed