Figure 8. Schematic diagram illustrating molecular regulators of EC-pericyte tube co-assembly during capillary network formation.

(A) EC-pericyte co-cultures were established in the absence or presence of pharmacologic inhibitors (CIGS) or neutralizing agents that interfere with pericyte recruitment, and after 120 hr, cultures were fixed and stained with anti-CD31 antibodies. Representative confocal images of these cultures are shown. Bar equals 200 μm. (B) Schematic illustration of the key growth factors and peptides that stimulate EC tubulogenesis (EC Factors- IL-3, SCF, SDF-1α, FGF-2, Insulin) and pericyte recruitment to EC tube networks (Pericyte Factors- PDGF-BB, PDGF-DD, ET-1, TGFβs, HB-EGF) that are each necessary to create capillary networks. Combined blockade of the Pericyte Factors or their receptors markedly interferes with pericyte invasion, recruitment, basement membrane deposition, and establishment of narrow and elongated networks of capillary tubes.