UCLA

Mesenchymal stem cells (MSCs) are a promising tool in regenerative medicine due to their capacity to differentiate into multiple lineages. In addition to MSCs isolated from bone marrow (BMSCs), adult MSCs are isolated from craniofacial tissues including dental pulp (DP) and periodontal ligament (PDL) tissues using various stem cell surface markers. However, there has been a lack of consensus on a set of surface makers that are reproducibly effective at isolating putative multipotent dental mesenchymal stem cells (DMSCs). In this study, we used different combinations of surface markers (CD51/CD140α, CD271, and STRO-1/CD146) to isolate homogeneous populations of DMSCs from heterogeneous dental pulp cells (DPCs) and periodontal ligament cells (PDLCs) and compared their capacity to undergo multilineage differentiation. Fluorescence-Activated Cell Sorting (FACS) revealed that 27.3% of DPCs were CD51+/CD140α+, 10.6% were CD271+, and 0.3% were STRO-1+/CD146+; whereas 24% of PDLCs were CD51+/CD140α+, 0.8% were CD271+, and 2.4% were STRO-1+/CD146+. Sorted cell populations were further assessed for their multipotent properties by inducing odonto/osteogenic, chondrogenic, and adipogenic differentiation. All three subsets of isolated DMSCs exhibited differentiation capacity into odonto/osteogenic and chondrogenic lineages but with varying degrees. CD271+ DMSCs demonstrated the greatest odonto/osteogenic potential with strong induction of odonto/osteogenic and periodontal markers such as DLX5, RUNX2, BGLAP, DMP1, DSPP, and PLAP-1. Based on these results, the role of CD271 in odontogenic differentiation was further evaluated. CD271 is one of the receptors which Nerve Growth Factor (NGF) exerts its biological effects through. Although NGF is known for its role in the the development and maintenance of the nervous system, it’s capability to promote odontogenic differentiation has made it an interesting candidate for its role as a mineralizing agent in regenerative therapies. We found that exogenous treatment of NGF further increased odonotogenic potential of CD271+ DMSCs from DP with induction of odontogenic markers DLX5, RUNX2, and BGLAP, and increased MAPK, AKT, MTOR, and NF-B signaling pathways in a time dependent manner. Furthermore, knockdown of tropomyosin trkA tyrosine kinase receptor (trkANGFR) and low affinity nerve growth factor receptor (p75NTR/CD271/LNGFR) decreased odontogenic differentiation of CD271+ DMSCs. Our study provides important insights into the use of DMSCs and growth factors for regenerative therapies in dentistry, and improves our understanding of the molecular mechanisms involved in odontogenic differentiation