Human procollagen type I surface-modified PHB-based non-woven textile scaffolds for cell growth: preparation and short-term biological tests

Poly(2-oxazoline) Matrices with Temperature-Dependent Solubility-Interactions with Water and Use for Cell Culture

In this work, we studied the stability of matrices with temperature-dependent solubility and their interactions with water at physiological temperature for their application in cell culture in vitro. Gradient copolymers of 2-isopropyl- with 2-n-propyl-2-oxazoline (P(iPrOx-nPrOx)) were used to prepare the matrices. The comonomer ratio during polymerization was chosen such that the cloud point temperature (T_CP) of the copolymer was below 37 °C while the glass transition (T_g) was above 37 °C. The role of the support for matrices in the context of their stability in aqueous solution was examined. Therefore, matrices in the form of both self-supported bulk polymer materials (fibrillar mats and molds) and polymer films supported on the silica slides were examined. All of the matrices remained undissolved when incubated in water at a temperature above T_CP. For the self-supported mats and molds, we observed the loss of shape stability, but, in the case of films supported on silica slides, only slight changes in morphology were observed. For a more in-depth investigation of the origin of the shape deformation of self-supported matrices, we analyzed the wettability, thickness, and water uptake of films on silica support because the matrices remained undeformed under these conditions. It was found that, above the T_CP of P(iPrOx-nPrOx), the wettability of the films decreased, but at the same time the films absorbed water and swelled. We examined how this specific behavior of the supported films influenced the culture of fibroblasts. The temperature-dependent solubility of the matrices and the possibility of noninvasive cell separation were also examined.

The Synthesis and Structural Characterization of Graft Copolymers Composed of γ-PGA Backbone and Oligoesters Pendant Chains

The novel copolymers composed of poly-γ-glutamic acid (γ-PGA) and oligoesters have been developed. The structures of the obtained copolymers including variety of end groups were determined at the molecular level with the aid of electrospray ionization multistage mass spectrometry (ESI-MSⁿ). The fragmentation experiment performed for the selected sodium adducts of the copolymers confirmed that the developed methods lead to the formation of graft copolymers composed of poly-γ-glutamic acid (γ-PGA) backbone and oligoesters pendant chains. Moreover, it was established that fragmentation of selected sodium adducts of graft copolymers proceeded via random breakage of amide bonds along the backbone and ester bonds of the oligoesters pendant chains. Considering potential applications of the synthesized copolymers in the area of biomaterials, the hydrolytic degradation under laboratory conditions and in vitro cytotoxicity tests were performed. The ESI-MSⁿ technique applied in this study has been proven to be a useful tool in structural studies of novel graft copolymers as well as their degradation products. Graphical Abstract ᅟ.

Nanofibrous poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate) scaffolds provide a functional microenvironment for cartilage repair

Articular cartilage defects, when repaired ineffectively, often lead to further deterioration of the tissue, secondary osteoarthritis and, ultimately, joint replacement. Unfortunately, current surgical procedures are unable to restore normal cartilage function. Tissue engineering of cartilage provides promising strategies for the regeneration of damaged articular cartilage. As yet, there are still significant challenges that need to be overcome to match the long-term mechanical stability and durability of native cartilage. Using electrospinning of different blends of biodegradable poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate), we produced polymer scaffolds and optimised their structure, stiffness, degradation rates and biocompatibility. Scaffolds with a poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate) ratio of 1:0.25 exhibit randomly oriented fibres that closely mimic the collagen fibrillar meshwork of native cartilage and match the stiffness of native articular cartilage. Degradation of the scaffolds into products that could be easily removed from the body was indicated by changes in fibre structure, loss of molecular weight and a decrease in scaffold stiffness after one and four months. Histological and immunohistochemical analysis after three weeks of culture with human articular chondrocytes revealed a hyaline-like cartilage matrix. The ability to fine tune the ultrastructure and mechanical properties using different blends of poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate) allows to produce a cartilage repair kit for clinical use to reduce the risk of developing secondary osteoarthritis. We further suggest the development of a toolbox with tailor-made scaffolds for the repair of other tissues that require a ‘guiding’ structure to support the body’s self-healing process.

Controlled drug release for tissue engineering

Tissue engineering is often referred to as a three-pronged discipline, with each prong corresponding to 1) a 3D material matrix (scaffold), 2) drugs that act on molecular signaling, and 3) regenerative living cells. Herein we focus on reviewing advances in controlled release of drugs from tissue engineering platforms. This review addresses advances in hydrogels and porous scaffolds that are synthesized from natural materials and synthetic polymers for the purposes of controlled release in tissue engineering. We pay special attention to efforts to reduce the burst release effect and to provide sustained and long-term release. Finally, novel approaches to controlled release are described, including devices that allow for pulsatile and sequential delivery. In addition to recent advances, limitations of current approaches and areas of further research are discussed.