PMC

Rhesus dental pulp stem/stromal cells (rDPSCs) have therapeutic potential in the central nervous system. The rDPSC graft increases ciliary neurotrophic factor (CNTF), vascular endothelial growth factor (VEGF), nerve growth factor (NGF), and fibroblast growth factor 2 (FGF-2), and thus increases endogenous neurogenesis. The increase in VEGF and NGF signaling promotes survival of these cells. FGF-2 signaling increases the differentiation potential to neural progenitor cells (NPCs), neurons, and mature glial cells. The rDPSC graft also recruits pre-existing, endogenous NPCs and neurons. By increasing local growth factor signaling, the rDPSC graft increases the overall number of NPCs and neurons at the site of the graft.

Rhesus dental pulp stem/stromal cells (rDPSCs) recruit endogenous neural cells and stimulate differentiation of new cells to mature neural cells. The rDPSC graft recruited pre-existing endogenous neural cells at 7 (A–D) and 30 (I–L) days compared with the contralateral, phosphate-buffered saline-injected hemisphere (E–H [7 days], M–P [30 days]). rDPSC implantation stimulated recruitment of Nestin⁺ (A, I) and βIII-tubulin⁺ (B, J) neural cells. (C, K): There was an increase only in glial fibrillary acidic protein-positive (GFAP⁺) astrocytes (D, L) and no increase in Iba1⁺ microglia/macrophages, (G, O and H, P, respectively) compared with the contralateral hemisphere. Insets show high-power confocal images at the heart of the cell graft as indicated by a white box. New cells had differentiated into (A, I) Nestin⁺, (B, J) βIII-tubulin⁺, and (C, K) GFAP⁺ at 7 and 30 days and into (D) Iba1⁺ cells at 7 days. Images at contralateral sides were captured by using the same exposure time. Scale bar = 100 μm. Abbreviations: BrdU, bromodeoxyuridine; DAPI, 4′,6-diamidino-2-phenylindole.

Rhesus dental pulp stem/stromal cells (rDPSCs) increase growth factor signaling. The rDPSC graft increases the amount of growth factor signaling at both 7 (A–D) and 30 (I–L) days compared with the contralateral, phosphate-buffered saline-injected hemisphere (E–H and M–P, respectively). (A): There was a robust increase in ciliary neurotrophic factor (CNTF) at 7 days and (J) vascular endothelial growth factor (VEGF) at 30 days, (K) substantial increases in nerve growth factor (NGF) at 30 days and (D) fibroblast growth factor (FGF) at 7 days, and small increases in (I) CNTF at 30 days and (B) VEGF at 7 days. There were no overt differences in (C) NGF at 7 days and (L) FGF at 30 days. Images at contralateral sides were captured by using the same exposure time. High-power confocal images show the expression of each growth factor by bromodeoxyuridine-positive (BrdU⁺) and surrounding cells at 7 and 30 days (inset images). Scale bar = 100 μm.

Rhesus dental pulp stem/stromal cells (rDPSCs) increase neural cell proliferation. Green fluorescent protein-rDPSCs were implanted into the right dentate gyrus of the hippocampus. The size of the graft was assessed at 1, 3, 5, 7, and 30 days after implantation. The graft was successful (1 day, A), but subsequently diminished in size (3–30 days, B–E). (A–E, inset images): High-magnification confocal images reveal the disruption of the rDPSC cell body into smaller fragments between 5–30 days, suggesting apoptosis or phagocytosis. (G–J): rDPSC implantation stimulated neural cell proliferation at days 3–30 after implantation, (L–O) compared with the contralateral, phosphate-buffered saline-injected hemisphere. There were no changes in the number of proliferating cells one day after rDPSC (F) or PBS implantation (K). Bromodeoxyuridine was injected every 12 hours for the first 7 days after implantation to label all dividing cells. New cells survived for at least 30 days. Images at contralateral sides were captured using the same exposure time. Scale bar = 100 μm.

Characterization of rhesus monkey dental pulp stem/stromal cells (rDPSCs). (A): Expression of stem cell (Nanog, Rex-1, Oct-4) and osteogenic (osteonectin, osteocalcin, and osteopontin) markers was determined by reverse-transcription polymerase chain reaction. (B): The proliferation rate of rDPSCs was compared between passages 3, 4, 5, and 6. (C): rDPSC samples were collected at passages 5 (P5) and 17 (P17) for telomere analysis. No obvious change in telomere length was observed. (D): Cell surface antigen profile was determined by using a total of thirteen cell surface antigens. The expression profile of rDPSCs was comparable with human bone marrow stem/progenitor cells (hBMSCs) and the published profiles of rhesus BMSCs (rBMSCs) [], hBMSCs [], and human DPSCs (hDPSCs) [, ]. Both DPSCs and BMSCs derived from rhesus monkey and human share almost identical expression profiles on common cell surface antigens. rDPSCs also share similar morphology to that of rBMSCs, hBMSCs and hDPSCs. (Ea): rDPSCs are spindle and fibroblast like cells, and are capable of differentiating into (Eb) osteogenic, (Ec) adipogenic, and (Ed) chondrogenic lineages. Scale bar = 5 μm. Abbreviation: GAPDH, glyceraldehyde-3-phosphate dehydrogenase.