Distinctive characteristics of articular cartilage such as avascularity and low chondrocyte conversion rate present numerous challenges for orthopedists. Tissue engineering is a novel approach that ameliorates the regeneration process by exploiting the potential of cells, biodegradable materials, and growth factors. However, problems exist with the use of tissue-engineered construct, the most important of which is scaffold-cartilage integration. Recently, many attempts have been made to address this challenge via manipulation of cellular, material, and biomolecular composition of engineered tissue. Hence, in this review, we highlight strategies that facilitate cartilage-scaffold integration. Recent advances in where efficient integration between a scaffold and native cartilage could be achieved are emphasized, in addition to the positive aspects and remaining problems that will drive future research.
Wound healing remains a burdensome healthcare problem
due to moisture
loss and bacterial infection. Advanced hydrogel dressings can help
to resolve these issues by assisting and accelerating regenerative
processes such as cell migration and angiogenesis because of the similarities
between their composition and structure with natural skin. In this
study, we aimed to develop a keratin-based hydrogel dressing and investigate
the impact of the delivery of LL-37 antimicrobial peptide using this
hydrogel in treating full-thickness rat wounds. Therefore, oxidized
(keratose) and reduced (kerateine) keratins were utilized to prepare
10% (w/v) hydrogels with different ratios of keratose and kerateine.
The mechanical properties of these hydrogels with compressive modulus
of 6–32 kPa and tan δ <1 render them suitable
for wound healing applications. Also, sustained release of LL-37 from
the keratin hydrogel was achieved, which can lead to superior wound
healing. In vitro studies confirmed that LL-37 containing
25:75% of keratose/kerateine (L-KO25:KN75) would result in significant
fibroblast proliferation (∼85% on day 7), adhesion (∼90
cells/HPF), and migration (73% scratch closure after 12 h and complete
closure after 24 h). Also, L-KO25:KN75 is capable of eradicating both
Gram-negative and Gram-positive bacteria after 18 h. According to in vivo assessment of L-KO25:KN75, wound closure at day
21 was >98% and microvessel density (>30 vessels/HPF at day
14) was
significantly superior in comparison to other treatment groups. The
mRNA expression of VEGF and IL-6 was also increased in the L-KO25:KN75-treated
group and contributed to proper wound healing. Therefore, the LL-37-containing
keratin hydrogel ameliorated wound closure, and also angiogenesis
was enhanced as a result of LL-37 delivery. These results suggested
that the L-KO25:KN75 hydrogel could be a sustainable substitute for
skin tissue regeneration in medical applications.
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