Angiogenic Potential of VEGF Mimetic Peptides for the Biofunctionalization of Collagen/Hydroxyapatite Composites

Abstract

Currently, the focus on bioinspired concepts for the development of tissue engineering constructs is increasing. For this purpose, the combination of collagen (Coll) and hydroxyapatite (HA) comes closest to the natural composition of the bone. In order to confer angiogenic properties to the scaffold material, vascular endothelial growth factor (VEGF) is frequently used. In the present study, we used a VEGF mimetic peptide (QK) and a modified QK-peptide with a poly-glutamic acid tag (E7-QK) to enhance binding to HA, and analyzed in detail binding efficiency and angiogenic properties. We detected a significantly higher binding efficiency of E7-QK peptides to hydroxyapatite particles compared to the unmodified QK-peptide. Tube formation assays revealed similar angiogenic functions of E7-QK peptide (1µM) as induced by the entire VEGF protein. Analyses of gene expression of angiogenic factors and their receptors (FLT-1, KDR, HGF, MET, IL-8, HIF-1α, MMP-1, IGFBP-1, IGFBP-2, VCAM-1, and ANGPT-1) showed higher expression levels in HUVECs cultured in the presence of 1µM E7-QK and VEGF compared to those detected in the negative control group without any angiogenic stimuli. In contrast, the expression of the anti-angiogenic gene TIMP-1 showed lower mRNA levels in HUVECs cultured with E7-QK and VEGF. Sprouting assays with HUVEC spheroids within Coll/HA/E7-QK scaffolds showed significantly longer sprouts compared to those induced within Coll/HA/QK or Coll/HA scaffolds. Our results demonstrate a significantly better functionality of the E7-QK peptide, electrostatically bound to hydroxyapatite particles compared to that of unmodified QK peptide. We conclude that the used E7-QK peptide represents an excellently suited biomolecule for the generation of collagen/hydroxyapatite composites with angiogenic properties.

Pre-Conditioning with IFN-γ and Hypoxia Enhances the Angiogenic Potential of iPSC-Derived MSC Secretome

“…Currently, we developed collagen/hydroxyapatite composites with good angiogenic properties by incorporating VEGF-mimetic peptides [36]. However, a cell type with proangiogenic properties could further support construct endothelialization in situ.…”

“…To evaluate the functionality of differently conditioned iMSCs secretomes also in the 3D-culture, sprouting assays with HUVEC spheroids were performed within collagen/hydroxyapatite (coll/HA) composite scaffolds. We described the generation of these scaffolds in a previous work [36]. HUVEC spheroids were incorporated into coll/HA scaffolds and incubated in the presence of differently pre-conditioned iMSCs secretomes (IFN-H, IFN-N, CO-H, and CO-N groups).…”

Biofabricating the Vascular Tree in Engineered Bone Tissue

“…This led scientists to explore techniques which would promote and accelerate rapid host capillary ingrowth upon implantation such as functionalization of scaffolds with angiogenic growth factors [73][74][75][76][77]. Alternatively, scaffold design i.e., surface topography, porosity, pore size and pore interconnectivity are other well-known factors to affect vascular cell behavior and degree of vascular invasion [78][79][80][81][82][83][84].…”

In vitro dynamic perfusion of prevascularized OECs-DBMs (outgrowth endothelial progenitor cell - demineralized bone matrix) complex fused to recipient vessels in an internal inosculation manner

“…The critical factor for survival and function of tissue-engineered bone after implantation is rapid access to adequate blood perfusion [ 11 ]. With this in mind, many researchers have focused on the use of pro-vascular growth-related factors to stimulate angiogenesis in the recipient region and on the ingrowth of tissue-engineered products [ 2 , 4 ]. However, studies have confirmed that the limit of human microvascular growth rate is about 5 μm/h in physiological state [ 12 , 13 ].…”