Has been reported to induce at least Marimastat outgrowth of ECs [9], BMSC-conditioned medium showed no effect on ECs [33]. Furthermore, investigating the gene expression profile gives an opportunity to observe differences in intercellular communication in ASCs compared to BMSCs. While BMSCs represent the state of the art cell type of MSCs in these co-culture systems, ASCs might be preferred over BMSCs in future. ASCs can be harvested with a less invasive technique and are in general present in higher numbers in adipose tissue than BMSCs are in bone marrow [55]. Differences between BMSCs and ASCs in coculture with ECs are summarized in Table 1.Functionality of engineered microvessels with mesenchymal stem cells (MSCs) in vivoSince analysis of the functionality of microvessel-like structures in vitro is difficult to prove, different in vivo PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/22763976 models have been established. EPCs co-cultured with BMSCs show formation of vascular structures in Matrigel as well as in type I collagen, fibrin, and PuraMatrix, an engineered peptide hydrogel, 7 days after the ECMcontaining cells were injected subcutaneously in immunodeficient mice [14, 56]. Such structures could also beTable 1 Differences between BMSCs and ASCs in co-culture with ECsBMSCs 3D matrix used for co-culture Pericytic marker Paracrine factors Fibrin [9, 38, 39, 42, 43, 49], PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/3081428 polyurethane [37], type I collagen [38], fibrin + type I collagen in different ratios [38] -SMA [9, 37, 46], NG2 [37], CD146 [37] HGF, TIMP1, TIMP2 [9] ASCs Fibrin [9, 33, 43, 51, 52]-SMA [9, 50], NG2 [33] HGF, TNF- [51], PD-ECGF, FGF-2, MMP-9, Ang-2, pentraxin-3 [33], ECM proteins: collagen IV, fibronectin [50] CD31 , VE-cadherin , VEGFR-2 , vWF [33]Altered gene expressionFGF-2 , TGFB1 , VEGFA [42], vWF , CD31 , VE-cadherin , angiopoietin-related protein 4 , CD34 , CD93 , CDH5 [45], MMPs [39] HUVECs [9, 37?9, 43, 45, 46, 48, 49],EPCs [37], ECFCs [42] Yes (in contrast to fibroblasts) [39, 49]Endothelial cell type MMPs important for network formation and ECM degradationHUVECs [9, 33, 43, 51], OECs [33, 52] Yes [52], to a lesser extent as plasmin family proteases [51]BMSCs and ASCs have different effects on ECs and show altered behavior concerning pericytic marker expression, paracrine factors, gene expression, and importance of MMPs for network formation. Furthermore, different matrices as well as different EC types were used to investigate effects of MSCs on ECsPill et al. Cell Regeneration (2015) 4:Page 8 ofFig. 4 OECs/ASCs co-culture in fibrin subcutaneously implanted in a nude mouse model. ASCs (100,000) were mixed with OECs (100,000) in fibrin (2.5 mg/ml) and pre-vascularized for 1 week in vitro before subcutaneous implantation in a nude mouse. One week later, the clots were excised and processed for immunohistochemistry with anti-human vimentin (left panel). Tail-vein-injected FITC-labeled wheat germ agglutinin (WGA) was found in the lumen of these vessels, indicating perfusion and thus functionality (right panel). Scale bar = 50 mfound after 2 weeks when a collagen/fibronectin matrix containing EPC-ASC co-cultures was implanted [57]. Even 7 weeks after injection of Matrigel containing ECFCBMSC co-cultures in nude mice, durable neo-vessel formation was found in Matrigel plugs [58]. A subset of pre-vascular structures formed in in vitro cultured spheroids containing HUVECs as well as ASCs was able to anastomose with the host vascular system of athymic male nude mice [13]. Moreover, co-cultures of OECs and ASCs in fibrin.
