Bayer School of Natural and Environmental Sciences
John S. Doctor
Ellen S. Gawalt
Kyle W. Selcer
Phil G. Campbell
Richard P. Elinson
differentiation, Insulin-like growth factor, PAPP-A, pregnancy associated plasma protein-A, proliferation
Pregnancy associated plasma protein-A (PAPP-A) plays an important role in the activity of the Insulin-like Growth Factor (IGF) family by proteolytically cleaving IGF-Binding Protein-4 (IGFBP-4) causing it to dissociate from IGF-I in vivo. This increases the bioavailability of IGF-I, allowing IGF-I to participate in growth and development. My goal was to evaluate the ability of PAPP-A to directly stimulate proliferation and differentiation of human adult mesenchymal stem cells (hAMSC) cells in vitro.
Commercially available PAPP-A, comprised of a heterotetrameric complex consisting of two PAPP-A subunits and two pro-MBP (proform of eosinophil major basic protein) subunits, was used in the following studies. Proliferation of hAMSC in response to PAPP-A was evaluated via CyQUANT and BrdU incorporation. Cells were arrested at G0 prior to treatment with 200 ng/mL PAPP-A. CyQUANT and BrdU incorporation results did not show statistically significant evidence of proliferation of hAMSC when treated with PAPP-A.
To test for differentiation, hAMSC were treated with mesenchymal stem cell growth medium -- MSCGM (negative control), an osteogenic supplement (positive control) or 200 ng/mL PAPP-A in MSCGM for multiple time points. hAMSC were harvested for RNA extraction followed by qPCR analysis to detect osteoblastic differentiation via multiple marker genes. qPCR results showed a statistically significant increase in Runx2 and alkaline phosphatase gene expression in hAMSC when treated with PAPP-A for 12 and 18 hours respectively.
My results indicate that addition of PAPP-A to cell culture medium does not affect proliferation of hAMSC. However, treatment with PAPP-A for 12 and 18 hours increases Runx2 and alkaline phosphatase gene expression respectively in hAMSC suggesting that PAPP-A plays a role in osteoblast differentiation in an in vitro environment. Further elucidation of this role is necessary to determine PAPP-A's involvement in osteoblast development and its potential therapeutic role in bone degenerative diseases such as osteoporosis.
Hott, S. (2006). The Effect of PAPP-A on the Proliferation and Differentiation of MG-63 and Human Adult Mesenchymal Stem Cells (Master's thesis, Duquesne University). Retrieved from https://dsc.duq.edu/etd/665