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Scaffolds for bone tissue regeneration should provide the right cues for stem cell adhesion and proliferation, but also lead to their osteogenic differentiation. Hydrogels of modified platelet lysates (PLMA) show the proper mechanical stability for cell encapsulation and contain essential bioactive molecules required for cell maintenance. We prepared a novel PLMA-based nanocomposite for bone repair and regeneration capable of releasing biofactors to induce osteogenic differentiation. Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) were encapsulated in PLMA hydrogels containing bioactive mesoporous silica nanoparticles previously loaded with dexamethasone and functionalized with calcium and phosphate ions. After 21 d of culture, hBM-MSCs remained viable, presented a stretched morphology, and showed signs of osteogenic differentiation, namely the presence of significant amounts of alkaline phosphatase, bone morphogenic protein-2 and osteopontin, hydroxyapatite, and calcium nodules. Developed for the first time, PLMA/MSNCaPDex nanocomposites were able to guide the differentiation of hBM-MSCs without any other osteogenic supplementation.

Skin defects are amongst the main causes of morbidity and mortality worldwide, which account for significantly high socioeconomic costs. Today, much attention is being paid to tissue engineering and biomaterials strategies for skin regeneration, and among them, there is increasing interest in using multigradient biomaterials. Gradient-based approaches are an emerging trend in tissue engineering for the homogeneous delivery of therapeutic agents by using biomaterials. Several studies have acknowledged that wound repair mechanisms could be enhanced through biomimicking physicochemical properties of different skin layers. In addition, in different layers of skin tissue, cells experience various physicochemical gradients, which potentially regulate their behaviors. Therefore, interface tissue engineering and biomaterials approaches are gaining increasing attention for skin regeneration through the incorporation of physicochemical gradients within the engineered constructs. This review first presents a necessary overview of the biological properties of skin tissue and its changes during repair in different tissue injuries. Fundamental issues and necessities of using different types of gradient scaffolds and interface tissue engineering strategies for skin regeneration are addressed. The focus of this review is on describing current progress in designing gradient scaffolds for controlling and directing cellular and molecular responses in skin tissue. The main used fabrication approaches, including both traditional and advanced methods for designing multigradient scaffolds, are also discussed. Keywords: Skin gradient, Wound healing, Physical gradient, Chemical gradient, Scaffold

Nanoliposomes are widely used as delivery vehicles for active compounds. Nanoliposomes from rapeseed phospholipids were incorporated into interpenetrating polymer network hydrogels of gelatin methacryloyl and alginate. The multiscale physicochemical properties of the hydrogels are studied both on the surface and through the thickness of the 3D network. The obtained composite hydrogels exhibited strong mechanical properties and a highly porous surface. The blend ratio, as well as the concentration of nanoliposomes, affects the properties of the hydrogels. Nanofunctionalized hydrogels induced keratinocyte ​growth. These advantageous characteristics may open up many applications of the developed hydrogels in drug delivery and tissue engineering.