Collagen I hydrogel microstructure and composition conjointly regulate vascular network formation

Abstract

Neovascularization is a hallmark of physiological and pathological tissue remodelling that is regulated in part by the extracellular matrix (ECM). Collagen I hydrogels or Matrigel are frequently used to study vascular network formation; however, in isolation these materials do not typically mimic the integrated effects of ECM structure and composition that may influence endothelial cells in vivo. Here, we have utilized microfabricated 3D culture models to control collagen I microstructure in the presence and absence of Matrigel and tested the effect of these variations on vascular network formation by human cerebral microvascular endothelial cells (hCMECs). Varied collagen microarchitecture was achieved by adjusting the gelation temperature and subsequently confirmed by structural analysis. Casting at colder temperature increased collagen fiber thickness and length, and inclusion of Matrigel further pronounced these differences. Interestingly, presence of Matrigel affected vascular network formation by modulating hCMEC growth, whereas altered collagen fiber structure impacted the morphology and maturity of the developed vascular network. These differences were related to substrate-dependent changes in interleukin-8 (IL-8) secretion and were functionally relevant as vascular networks preformed in more fibrillar, Matrigel-containing hydrogels promoted angiogenic sprouting. Our studies indicate that collagen hydrogel microstructure and composition conjointly regulate vascular network formation with implications for translational and basic science approaches.

Quantification of iPSC-derived vascular networks in novel phototunable angiogenic hydrogels

“…This architecture is reminiscent of cold-cast collagen, which indicates that this change in fiber formation could be accounted for by the additional time it takes the user to pipette and mix the seven constituent components of the IPN hydrogels at room temperature. It has been previously determined that cold-cast collagen, which is characterized by longer, thicker fibers, better promoted endothelial cell branching and collagen IV deposition [47].…”

Bioactive glass ions for in vitro osteogenesis and microvascularization in gellan gum‐collagen hydrogels

“…The immunofluorescence imaging results showed that the BaG EM‐OM condition was required for strong osteocalcin production, whereas the EGM‐2 condition supported strong CD31 production and vessel‐like structure formation, similarly to a report by Ma et al (). While various in vitro approaches for vascularized hydrogel constructs have been explored (Cerqueira et al, ; McCoy, Seo, Choi, & Fischbach, ), importantly for novelty, we produced capillary‐like growth in 3D GG‐COL composite hydrogel with the added mechanical stability offered by GG compared to COL alone (Vuornos et al, ). Importantly for novelty, the efficient BaG EM‐OM osteogenic capacity was further demonstrated by strong staining of cell‐secreted mineralized matrix hydroxyapatite residues in both the BaG EM‐OM media conditions, and even accentuated with OM preconditioning of hASCs.…”

Biofabrication Strategies and Engineered In Vitro Systems for Vascular Mechanobiology

“…[ 55,81 ] For example, properties of collagen have been tuned via: 1) cold‐casting with Matrigel to enhance fibrillar assembly, 2) freeze drying to create anisotropic or aligned pores, 3) crosslinking at varying pH, temperature, concentration, and cell densities to tune stiffness, fiber thickness, length, and density, all of which influence self‐assembly of microvasculature. [ 53–58 ] Similarly, fibrin gels (which have shorter, thinner, densely meshed fibrils compared to collagen) with modifications to matrix density and induction of uniaxial cyclic pre‐stress have been used in sprouting angiogenesis assays. [ 61,62,190,191 ]…”