Abstract

Ischaemic heart disease (IHD) presents a significant burden on global morbidity, healthcare costs and patient wellbeing, therefore novel therapeutic methods for IHD are urgently needed. A family of proteins demonstrating potential in therapeutic angiogenesis is the insulin like growth factor binding proteins (IGFBPs). The family of IGFBPs (IGFBP-1-7) modulate IGF bioactivity and bioavailability. Several members of the IGFBP family exert IGF-independent cellular effects and are signalling molecules implicated in many physiological processes, including angiogenesis, which may be exploited therapeutically. IGFBP-2 possesses IGF binding domains, an Arg-Gly-Asp integrin-recognition motif and heparin-binding domains (HBDs), therefore promoting high affinity IGF binding, integrin recruitment and glycosaminoglycan interactions (via the HBD). IGFBP-2 possesses a nuclear localisation sequence, enabling its entry into the nucleus.

The effect of IGFBP-2 on angiogenic signalling pathways was investigated using Human Umbilical Vein Endothelial Cells (HUVECs). In vitro angiogenic assays were employed to study the angiogenic properties of IGFBP-2 in HUVECs.

HUVECs possessed highest endogenous expression levels of IGFBP-2 across a range of different cell types. IGFBP-2 stimulated HUVECs exhibited dose- and time-dependent enhancement in AKT activation. Maximum Akt phosphorylation was achieved with 200 ng/ml IGFBP-2. HUVECs stimulated with IGFBP-2 at different time intervals demonstrated immediate Akt activation at 15 minutes. Addition of IGFBP-2 to HUVECs significantly enhanced cell adhesion, migration and tube formation.

Future work involves investigating the mechanisms involved within the role of IGFBP-2 in angiogenesis by exploring each domain individually. In vivo studies are planned to confirm in vitro findings, supporting IGFBP-2 as a potential novel therapeutic for angiogenesis.