Identification of myogenic-endothelial progenitor cells in the interstitial spaces of skeletal muscle

Abstract

Putative myogenic and endothelial (myo-endothelial) cell progenitors were identified in the interstitial spaces of murine skeletal muscle by immunohistochemistry and immunoelectron microscopy using CD34 antigen. Enzymatically isolated cells were characterized by fluorescence-activated cell sorting on the basis of cell surface antigen expression, and were sorted as a CD34+ and CD45− fraction. Cells in this fraction were ∼94% positive for Sca-1, and mostly negative (<3% positive) for CD14, 31, 49, 144, c-kit, and FLK-1. The CD34+/45− cells formed colonies in clonal cell cultures and colony-forming units displayed the potential to differentiate into adipocytes, endothelial, and myogenic cells. The CD34+/45− cells fully differentiated into vascular endothelial cells and skeletal muscle fibers in vivo after transplantation. Immediately after sorting, CD34+/45− cells expressed only c-met mRNA, and did not express any other myogenic cell-related markers such as MyoD, myf-5, myf-6, myogenin, M-cadherin, Pax-3, and Pax-7. However, after 3 d of culture, these cells expressed mRNA for all myogenic markers. CD34+/45− cells were distinct from satellite cells, as they expressed Bcrp1/ABCG2 gene mRNA (Zhou et al., 2001). These findings suggest that myo-endothelial progenitors reside in the interstitial spaces of mammalian skeletal muscles, and that they can potentially contribute to postnatal skeletal muscle growth.

Identity, developmental restriction and reactivity of extralaminar cells capping mammalian neuromuscular junctions

“…Next, we looked for possible cell-surface markers of NMJcapping cells. A stem cell population located in interstitial spaces of skeletal muscle, outside the basal lamina, has been identified previously and isolated by immunostaining for the hematopoietic stem cell marker CD34 (Torrente et al, 2001;Tamaki et al, 2002). We found that the surfaces of NMJ-capping cells showed uniform, faint immunostaining for CD34 (Fig.…”

Searching for common stem cells of the hepatic and hematopoietic systems in the human fetal liver: CD34+ cytokeratin 7/8+ cells express markers for stellate cells

“…3C and 3D. Although CD34 is a well characterized marker of hematopoietic precursors, some nonhematopoietic cells also express this marker (17,18,31,32). Consistent with our findings, CK7/8 has previously not been found in hematopoietic cells (9).…”

Multidrug resistance mediated by the breast cancer resistance protein BCRP (ABCG2)

“…Expression of Bcrp1 was noted in CD34 þ /CD45 À murine myogenic-endothelial progenitor cells, which are resident in the interstitial spaces of mammalian skeletal muscle (Tamaki et al, 2002). BCRP expression has also been demonstrated in multipotential progenitor cells in islets isolated from adult human pancreas cells (Lechner et al, 2002).…”