以干细胞和内皮祖细胞(EPC)为细胞治疗手段促进缺血性疾病的血管形成是再生医学研究的热门领域。EPC存在于骨髓、外周血和脂肪组织中。自体EPC在获取时是一创伤性过程。本研究利用容易获取的牙髓来寻求EPC的替代来源。我们一CD31和CD146为筛选标志从牙髓侧群细胞中分离出一亚群，CD31(-)CD146(-)CD34(+)VEGFR2/Flk1(+)亚群与EPC类似，与造血系细胞不同在于CD11b、CD14、CD45为阴性表达。这类亚群细胞具有高增殖和迁移活性、多向分化潜能，包括血管形成能力。在小鼠后肢缺血模型中，这类亚群细胞的局部移植可产生细胞归巢、血流加快和毛细血管形成。移植的细胞在新生血管周围并表达多种促血管形成因子，如VEGF-A, G-CSF, GM-CSF和MMP3。这类细胞的条件培养液对人脐静脉内皮细胞有促分裂和抗凋亡的作用。总之，牙髓侧群细胞中的这类亚群细胞可作为组织再生中促血管发生和形成的新的干细胞来源。

Stem Cells. 2008 Jun 26. [Epub ahead of print]

A Novel Stem Cell Source for Vasculogenesis in Ischemia: Subfraction of Side Population Cells from Dental Pulp.

Iohara K, Zheng L, Wake H, Ito M, Nabekura J, Wakita H, Nakamura H, Into T, Matsusita K, Nakashima M.

Department of Oral Disease Research, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522, Japan.

Cell therapy with stem cells and endothelial progenitor cells (EPCs) to stimulate vasculogenesis as a potential treatment for ischemic disease is an exciting area of research in regenerative medicine. EPCs are present in bone marrow, peripheral blood, and adipose tissue. Autologous EPCs, however, are obtained by invasive biopsy, a potentially painful procedure. An alternative approach is proposed in this investigation. Permanent and deciduous pulp tissue is easily available from teeth after extraction without ethical issues and has potential for clinical use. We isolated a highly vasculogenic subfraction of side population (SP) cells based on CD31 and CD146, from dental pulp. The CD31(-);CD146(-) SP cells, demonstrating CD34(+) and VEGFR2/Flk1(+), were similar to EPCs. These cells were distinct from the hematopoietic lineage as CD11b, CD14, and CD45 mRNA were not expressed. They showed high proliferation and migration activities and multi-lineage differentiation potential including vasculogenic potential. In models of mouse hindlimb ischemia, local transplantation of this subfraction of SP cells resulted in successful engraftment and an increase in the blood flow including high density of capillary formation. The transplanted cells were in proximity of the newly formed vasculature and expressed several proangiogenic factors, such as VEGF-A, G-CSF, GM-CSF and MMP3. Conditioned medium from this subfraction showed the mitogenic and anti-apoptotic activity on human umbilical vein endothelial cells (HUVECs). In conclusion, subfraction of SP cells from dental pulp is a new stem cell source for cell-based therapy to stimulate angiogenesis/vasculogenesis during tissue regeneration.