Quantitative estimates of vascularity in a collagen-based cell scaffold containing basic fibroblast growth factor by noninvasive near-infrared spectroscopy for regenerative medicine

Objective: Successful tissue regeneration requires cells with high proliferative and differentiation potentials as well as an environment that promotes regeneration. Since cell scaffolds and growth factors provide such an environment and also induce angiogenesis and cell proliferation, we examined the hemoglobin content of implanted collagen-based cell scaffolds containing the angiogenic factor, basic fibroblast growth factor (bFGF), in vivo with noninvasive near infrared spectroscopy (NIRS). Background Data: Angiogenesis within cell scaffolds is typically determined by histological examination for endothelial cell markers. Unfortunately, this approach requires removal of tissue and scaffold invasively. Materials and Methods: We compared the hemoglobin content of implanted collagen-based cell scaffold as measured by NIRS to the hemoglobin content measured with a conventional invasive hemoglobin assay. Noninvasive NIRS recordings were performed with a custom-built near-infrared spectrometer using light guide-coupled reflectance measurements. Results: NIRS recordings revealed that absorbance increased after implantation of collagen scaffolds containing bFGF. This result correlated (R-2 = 0.93) with a subsequent conventional hemoglobin assay. Conclusion: The NIRS technique provides a noninvasive method for measuring the degree of vascularization in cell scaffolds. This technique may be advantageous for monitoring angiogenesis within different cell scaffolds, a prerequisite for effective tissue regeneration.