The objective of the study was to produce three-dimensional and porous nanofiber reinforced hydrogel scaffolds that can mimic the hydrated composite structure of the cartilage extracellular matrix. In this regard, wet-electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofiber reinforced carboxymethyl chitosan-silk fibroin (PNFs/CMCht-SF) hydrogel composite scaffolds that were chemically cross-linked by poly(ethylene glycol) diglycidyl ether (PEGDE) were produced. To the best of our knowledge, this is the first study in cartilage regeneration where a three dimensional porous spongy composite scaffold was obtained by the dispersion of wet-electrospun nanofibers within a polymer matrix. All of the produced hydrogel composite scaffolds had an interconnected microporous structure with well-integrated PHBV nanofibers on the pore walls. The scaffold comprising an equal amount of PEGDE and polymer (PNFs/CMCht-SF1:PEGDE1) demonstrated comparable water content (91.4 ± 0.7%), tan δ (0.183 at 1 Hz) and compressive strength (457 ± 85 kPa) values to that of articular cartilage. Besides, based on the histological analysis, this hydrogel composite scaffold supported the chondrogenic differentiation of bone marrow mesenchymal stem cells. Consequently, this hydrogel composite scaffold presented a great promise for cartilage tissue regeneration.

Material science and engineering are the sources of divergent emerging technologies, since all the modifications and developments are being made to reach a novel biomaterial to fulfill the requirements of biomedical applications, the first important feature is the biocompatibility of the new advanced material. In this chapter, the general biocompatibility concept, test systems to determine biocompatibility, examples of bioinspired materials and their altered biocompatibility and future expectations from these novel bioinspired materials will be discussed.

In this study, scaffolds with polycaprolactone (PCL) and hydroxy apatite (HA) were produced. Their properties are not sufficient to be used alone. Oleic Acid (OA) and glycerol monooleate (GMO) as organic additives were selected for a homogeneous distribution of the ceramic material in the polymer matrix. Biocomposite materials were prepared with solvent casting-salt leaching technique using dichloromethane as the solvent. Salt was used as the porosifier. Materials were kept in simulated body fluid (SBF) to determine the bioactivity in vitro conditions. FTIR and EDX analyses for chemical characterization, tensile and compressive tests for mechanical properties, SEM analyses for surface properties and BET analyses for pore sizes, total surface areas and total pore volumes of scaffolds were performed. FTIR, EDX, and SEM analyses were repeated after SBF treatment. Pore diameters were highly increased with 3 and 20 wt% HA addition. Small amount of GMO addition is more effective on pore size. Mechanical properties of scaffolds were suitable for soft tissue applications, as smooth muscle cells, skin and cancellous bone. The cytotoxicity and cell proliferation on scaffolds were studied with smooth muscle cells (SMC) and L929 fibroblastic cells in vitro. No cytotoxic effect was observed for the scaffolds in both cell types. J. VINYL ADDIT. TECHNOL., 00:000-000, 2016.

IntroductionMany people of all ages all over the world suffer from serious bone diseases such as bone fractures, bone tumors, and osteoporosis. The limited treatment options for these disorders indicate a need for new therapies. Cellular therapy is one of the promising methods in orthopedic clinical trials (Pytlik et al., 2009;Seong et al., 2010). To date, the most popular cells used in cellular therapies are mesenchymal stem cells (MSCs). They can be isolated from different adult tissues such as the bone marrow, placenta, liver, adipose, periosteum, and testes (Vater et al., 2011). Adipose tissue is one of the most preferred sources because it can be obtained by less invasive methods and in larger quantities than the other adult tissues (Liu et al., 2007). Adipose tissue-derived MSCs (ADMSCs) have a great plasticity for variable cell types. For the characterization of ADMSC plasticity, one of the most widely accepted methods is differentiating them into osteoblasts, chondrocytes, and adipocytes in vitro (Vater et al, 2011).Recently, several experiments have been performed to demonstrate the existence of adipose tissue-derived progenitors that give rise to bone (Liu et al., 2007;Arrigoni et al., 2009;Song et al., 2011;Çapkın, 2012). It was reported Materials and methodsAll cell culture materials and differentiation reagents were purchased from Greiner Bio-One (Germany) and Sigma Chemical Co. (USA) respectively, unless otherwise noted. Alpha minimum essential medium (MEM) (HyClone, SH30007.04), Dulbecco's modified Eagle's medium (DMEM) (high glucose) (FG0435), fetal bovine serum (FBS) (S0115), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (L1613), gentamicin (A2710), phosphate buffered saline (PBS) (L1835), Hank's balanced salt solution Abstract: Mesenchymal stem cells (MSCs) can be found in many types of adult tissues such as the bone marrow, adipose, placenta, liver, and periosteum. Recently, adipose tissue-derived MSCs (ADMSCs) have become one the most preferred MSC types because of their fast proliferation rate, abundance, and high plasticity for variable cell types. It is known that ADMSCs are able to differentiate into various cells, including osteoblasts, so they are quite promising for orthopedic clinical trials. The present study aimed to compare the osteogenic differentiation conditions of MSCs from human adipose tissue (hADMSC) and those of MSCs from rat adipose tissue (rADMSC). Therefore, differentiation experiments with five different media and two (human and rat) ADMSC types were performed and the mineralization responses of hADMSCs and rADMSCs were different.

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