Meniscus lesions are among the most common orthopaedic injuries
which can ultimately lead to degeneration of the knee articular cartilage.
The human meniscus has a limited healing potential, partly due
to a poor vasculature, and thus meniscus regeneration using tissue
engineering strategies has recently been investigated as a promising
alternative to total/partial meniscectomy [1]. Advanced scaffolds for
tissue engineering of meniscus should be able to mimic and preserve
the asymmetric vascular network of this complex tissue, i.e. enable controlling
the segmental vascularization during the regeneration process.
Novel scaffolds were produced combining a silk polymeric matrix (12
wt%) [2] and the methacrylated gellan gum hydrogel (iGG-MA),
which has been shown to be able to prevent the ingrowth of endothelial
cells and blood vessels into the hydrogels [3,4]. The angiogenic/
anti-angiogenic potential of acellular and cell-laden silk-12 scaffolds
combined with iGG-MA hydrogel was investigated in vivo, using the
chick embryo chorioallantoic membrane (CAM) assay. For producing
the cell-laden scaffolds, human meniscus cells (HMC¢s) were isolated
from morphologically intact human menisci using an enzymatic-based
digestion and expanded using standard culture conditions. The HMC’sladen
hydrogel/silk scaffolds were produced by encapsulating the
HMC’s into a 2 wt% GG-MA hydrogel, followed by impregnation onto
the 12 wt% silk scaffold and ionic-crosslinking in a saline solution. A
CAM assay was used to investigate the control of segmental vascularization
of the acellular and HMC¢s-laden hydrogel/silk scaffolds by the
effect of GG-MA hydrogel, until day 14 of embryonic development.
The in vivo study allowed investigating the number of macroscopic
blood vessels converging to the implants. The evaluation of possible
inflammation and endothelial cells ingrowths was performed by histological
(haematoxylin and eosin - H&E - staining) and immunohistochemical
methods (SNA-lectin staining). When the silk-12 scaffold was
combined with the hydrogel, an inhibitory effect was observed as demonstrated
by the low number of convergent blood vessels. Results have
shown that iGG-MA hydrogel prevented the endothelial cells adhesion
and blood vessels infiltration into the HMC’s hydrogel/silk scaffolds,
after 4 days of implantation. This study showed that the hydrogel/silk
scaffolds enabled controlling the segmental vascularization, thus it can
possibly mimic the native vasculature architecture during meniscus
regeneration
