טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentKhutaba Alaa
SubjectVEGF release from nanofibers scaffold for angiogenesis
DepartmentDepartment of Medicine
Supervisors Assistant Professor Sarouji Samer
Dr. Hadar Zigdon
Full Thesis textFull thesis text - English Version


Abstract

Objectives:

Angiogenesis is critical in all aspects of tissue regeneration. The aim of this study is to develop an electrospun fibers scaffold that permits controlled release of recombinant human vascular endothelial growth factor (rhVEGF) to enhance angiogenesis.

Methods:

Scaffolds composed of core-shell fibers were fabricated by electrospinning process. The shell solution was composed of polycarpolactone 8% and polyethylene glycol (PEG) in various concentrations (0.25-3%) to produce pores of different sizes on the shell. The core solution was composed of polyethylene oxide (PEO) 4% and mixed with rhVEGF. SEM was used to characterize the scaffold and measure pore size. The releasing kinetics of rhVEGF was monitored by enzyme linked immunosorbent assay (ELISA). In-vitro biological activity of rhVEGF was determined by trans-well migration assay. In-vivo angiogenesis was evaluated by subcutaneous implantation of the scaffold in a mouse model. Recruitment of cells into the scaffold and angiogenesis was evaluated via confocal microscopy and histomorphometry, after 3 and 14 days.

Results:

Core-shell fibers of 6-8 µm diameters were obtained.   Mean pore size of the shell was 503.497±64 nm in 3%PEG and 205±60 nm in 1%PEG (p<0.05). A positive correlation between PEG concentration and pore size in the shell was found. Similarly, changes in PEG concentrations influenced rhVEGF release: burst release of rhVEGF was observed in the 3% PEG (large pores) scaffold; with a maximum release of 23% within 4h. While in the 1%PEG (smaller pores) scaffold, a more gradual release of rhVEGF was observed: 38% of rhVEGF was released within 18h. Transwell migration assay demonstrated that 1%PEG scaffold loaded with rhVEGF enhanced endothelial cells (EC) migration by 80 folds compared with negative control  (1%PEG scaffold without rhVEGF) P<0.05. Analysis of subcutaneous transplants (In-vivo model) showed: increased recruitment of cells in the test group after 3 days. Likewise, angiogenesis was significantly higher in the test group after 3 and 14 days (P<0.01)

Conclusion:

The results of this study suggest that PEG concentration in our co-electrospinning system, influenced pore size of the scaffold shell thereby modified hVEGF165 release kinetics. Released hVEGF165 promoted ECs migration in-vitro and significantly enhanced blood vessel formation in vivo.