gms | German Medical Science

Objective: The myoblast-mediated transfer of angiogenic genes is a cell-based approach for induction of therapeutic collateralization. In chronic cerebral hypoperfusion, we recently demonstrated successful implantation and fusion of primary monoclonal mouse-myoblasts in the non-ischemic temporal muscle of an experimental encephalomyosynangiosis (EMS). In the present study, we tested whether myoblast-mediated co-delivery of vascular endothelial growth factor-A (VEGF) and platelet derived growth factor-BB (PDGF) to the muscle/brain interface of an EMS improves collateralization and functional outcome in a model of cerebral hypoperfusion.

Method: Monoclonal mouse myoblasts expressing a reporter gene alone (control) or in combination with VEGF, PDGF or VEGF/PDGF were implanted into the temporal muscle of an EMS before permanent ipsilateral ICAO in C57/BL6 mice. Exogenous gene factor expression was confirmed by real-time PCR and western blot analysis. Hemodynamic impairment between days 0-84 after surgery was monitored by cerebrovascular reserve capacity (CVRC) assessment during cortical laser speckle imaging. On days 21, 42 and 84, transpial collateralization, vessel density and vessel maturity at the muscle/brain interface of the EMS were assessed after FITC-lectin perfusion and immunohistochemical staining. Cortical stroke volume and neuronal cell death after 60-minute MCAO were determined by MRI and immunohistochemical analysis.

Results: By day 21, co-expression of VEGF/PDGF resulted in an improved CVRC (VEGF/PDGF 37±15%; PDGF 27±8%; VEGF 30±11%; control 24±10%; p<0.05 for VEGF/PDGF vs. day 0), which was paralleled by significantly higher vessel density and pericyte coverage (VEGF/PDGF 68±11%; PDGF 63±9%; VEGF 47±6%; control 50±5%; p<0.05 for VEGF/PDGF vs. VEGF and control) of the collateral vasculature at the muscle/brain interface and in the parenchyma below the EMS. Functional and morphological findings were in line with an attenuated cortical stroke volume (VEGF/PDGF 34±12%; PDGF 47±13%; VEGF 41±12%; control 50±10%; p<0.05 for VEGF/PDGF vs. control) and decreased neuronal cell death (NeuN cells: VEGF/PDGF 391±145/mm²; PDGF 239±88/mm²; VEGF 189±119/mm²; control 181±95mm²; p<0.05 for VEGF/PDGF vs. all groups).

Conclusions: The balanced co-delivery of VEGF and PDGF may be harvested as a novel translational approach to facilitate indirect revascularization in patients at risk of ischemic stroke due to chronic cerebral hypoperfusion.