Differentiation of smooth muscle progenitor cells in peripheral blood and its application in tissue engineered blood vessels

Background： A major shortcoming in tissue engineered blood vessels （TEBVs） is the lack of healthy and easily attainable smooth muscle cells （SMCs）. Smooth muscle progenitor cells （SPCs）, especially from peripheral blood, may offer an alternative cell source for tissue engineering involving a less invasive harvesting technique. Methods： SPCs were isolated from 5-ml fresh rat peripheral blood by density-gradient centrifugation and cultured for 3 weeks in endothelial growth medium-2-MV （EGM-2-MV） medium containing platelet-derived growth factoroBB （PDGF BB）. Before seeded on the synthesized scaffold, SPC-derived smooth muscle outgrowth cell （SOC） phenotypes were assessed by immuno-fluorescent staining, Western blot analysis, and reverse transcription polymerase chain reaction （RT-PCR）. The cells were seeded onto the silk fibroin-modified poly（3-hydroxybutyrate-co-3-hydroxyhexanoate） （SF-PHBHHx） scaflblds by 6× 10^4 cells/cm^2 and cultured under the static condition for 3 weeks. The growth and proliferation of the seeded cells on the scaffold were analyzed by 3-（4,5-dimethylthiazol-2-yl）-diphenyltetrazolium bromide （MTT） assay, scanning electron microscope （SEM）, and 4,6-diamidino-2-phenylindole （DAPI） staining. Results： SOCs displayed specific ＂hill and valley＂ morphology, expressed the specific markers of the SMC lineage： smooth muscle （SM） a-actin, calponin and smooth muscle myosin heavy chain （SM MHC） at protein and messenger ribonucleic acid （mRNA） levels. RT-PCR results demonstrate that SOCs also expressed smooth muscle protein 22a （SM22a, a contractile protein, and extracellular matrix components elastin and matrix Gla protein （MGP）, as well as vascular endothelial growth factor （VEGF）. After seeded on the SF-PHBHHx scaffold, the cells showed excellent metabolic activity and proliferation. Conclusion： SPCs isolated from peripheral blood can be differentiated the SMCs in vitro and have an impressive growth potential in the biodegradable synthesized scaffold. Thus, SPCs may be a promising cell sointo urce for constructing TEBVs.

TGF-β1-induced LPP Expression Dependant on Rho Kinase during Differentiation and Migration of Bone Marrow-derived Smooth Muscle Progenitor Cells

Lipoma preferred partner(LPP) has been identified as a protein which is highly selective for smooth muscle progenitor cells(SMPCs) and regulates differentiation and migration of SMPCs,but mechanisms of LPP expression are not elucidated clearly.The aim of the present study was to discuss the mechanisms by which LPP expression is regulated in the differentiation and migration of SMPCs induced by TGF-β1.It was found that TGF-β1 could significantly increase the expression of LPP,smooth muscle α-actin,smooth muscle myosin heavy chain(SM-MHC),and smoothelin in SMPCs.Moreover,inactivation of Rho kinase(ROK) with ROK inhibitors significantly inhibited LPP mRNA expression in TGF-β1-treated SMPCs and mouse aortic smooth muscle cells(MAoSMCs).At the same time,LPP silencing with short interfering RNA significantly decreased SMPCs migration.In conclusion,LPP appears to be a ROK-dependant SMPCs differentiation marker that plays a role in regulating SMPCs migration.

Role of smooth muscle progenitor cells in vascular mechanical injury and repair

Smooth muscle progenitor cells are precursor cells that express both smooth muscle cell and stem cell markers,and can differentiate into smooth muscle cells under specific condition.Smooth muscle progenitor cells exist in many tissues,including bone marrow,blood vessels,peripheral blood,skeletal muscle,and kidney.Smooth muscle progenitor cells play an important role in the pathogenesis of vascular diseases,like atherosclerosis,vascular mechanical injury and repair,and vascular restenosis.Cytokines and growth factors are released upon injury,which promote smooth muscle progenitor cells to proliferate and differentiate into smooth muscle cells at injured sites.Massive growth of smooth muscle cells stabilizes atherosclerotic plaques and accelerates neointima formation,which leads to vascular restenosis.Some drugs are now used to inhibit the differentiation and proliferation of smooth muscle cells to prevent neointima formation.In this review,we have summarized some recent progress on the smooth muscle progenitor cells’origins,tissue distributions,and their role in vascular mechanical injury and repair.