Age and anatomical region related differences in vascularization of the porcine meniscus using micro-computed tomography imaging
Meniscal lesions in vascularized regions are known to regenerate while lack of vascular supply leads to poor healing. Here we developed and validated novel methodology for three-dimensional structural analysis of meniscal vascular structures with high-resolution micro-computed tomography ({micro}CT). We collected porcine medial menisci from 10 neonatal (not-developed meniscus, n-) and 10 adults (fully developed meniscus, a-). The menisci were cut into anatomical regions (anterior horn (n-AH & a-AH), central body (n-CB & a-CB), and posterior horn (n-PH & a-PH). Specimens were cut in half, fixed, and one specimen underwent critical point drying and {micro}CT imaging, while other specimen underwent immunohistochemistry and vascularity biomarker CD31 staining for validation of {micro}CT. Parameters describing vascular structures were calculated from {micro}CT. The vascular network in neonatal spread throughout meniscus, while in adult was limited to a few vessels in outer region, mostly on femoral side. a-AH, a-CB, and a-PH had three, five, and seven times greater vascular volume than neonate, respectively. Moreover, thickness of blood vessels, in three regions, was six times higher in adult than in newborn. Finally, a-PH appeared to have thicker blood vessels than both a-AH and a-CB. For the first time, critical point drying-based {micro}CT imaging allowed detailed three-dimensional visualization and quantitative analysis of vascularized meniscal structures. We showed more vascularity in neonatal menisci, while adult menisci had fewer and thicker vascularity especially limited to the femoral surface which is involved in load transmission response, thus suggesting how nutritional support in this area of the outer zone is more necessary.