Background: Magnesium (Mg)-based alloys are considered to be promising materials for implant application due to their excellent biocompatibility, biodegradability, and mechanical properties close to bone. However, low corrosion resistance and fast degradation are limiting their application. Mg–Ca alloys have huge potential owing to a similar density to bone, good corrosion resistance, and as Mg is essential for Ca incorporation into bone. The objective of the present work is to determine the in vitro degradation and in vivo performance of binary Mg– xCa alloy ( x = 0.5 or 5.0 wt%) to assess its usability for degradable implant applications. Methods: Microstructural evolutions for Mg– xCa alloys were characterized by optical, SEM, EDX, and XRD. In vitro degradation tests were conducted via immersion test in phosphate buffer saline solution. In vivo performance in terms of interface, biocompatibility, and biodegradability of Mg– xCa alloys was examined by implanting samples into rabbit femoral condyle for 2 and 4 weeks. Results: Microstructural results showed the enhancement in intermetallic Mg₂Ca phase with increase in Ca content. Immersion tests revealed that the dissolution rate varies linearly, with Ca content exhibiting more hydrogen gas evolution, increased pH, and higher degradation for Mg–5.0Ca alloy. In vivo studies showed good biocompatibility with enhanced bone formation for Mg–0.5Ca after 4 weeks of implantation compared with Mg–5.0Ca alloy. Higher initial corrosion rate with prolonged inflammation and rapid degradation was noticed in Mg–5.0Ca compared with Mg–0.5Ca alloy. Conclusions: The results suggest that Mg–0.5Ca alloy could be used as a temporary biodegradable implant material for clinical applications owing to its controlled in vivo degradation, reduced inflammation, and high bone-formation capability.

Microporous calcium phosphate based synthetic bone substitutes are used for bone defect healing. Different growth factor loading has been investigated for enhanced bone regeneration. The platelet is a cellular component of blood which naturally contains a pool of necessary growth factors that mediate initiation, continuation, and completion of cellular mechanism of healing. In this work, we have investigated the encapsulation and immobilization of platelet-rich plasma (PRP) with natural polymers like hyaluronic acid (HA) and gelatin (Gel) and loading them in a biphasic calcium phosphate (BCP) scaffold, for a synthetic-allologous hybrid scaffold. Effect of PRP addition in small doses was evaluated for osteogenic potential in vitro and in vivo. BCP (10%) mixed HA–Gel hydrogel with or without PRP, was loaded into a BCP sponge scaffold. We investigated the hydrogel-induced improvement in mechanical property and PRP-mediated enhancement in biocompatibility. In vitro studies for cytotoxicity, cell attachment, and proliferation were carried out using MC3T3-E1 pre-osteoblast cells. In in vitro studies, the cell count, cell proliferation, and cell survival were higher in the scaffold with PRP loading than without PRP. However, in the in vivo studies using a rat model, the PRP scaffold was not superior to the scaffold without PRP. This discrepancy was investigated in terms of the interaction of PRP in the in vivo environment.

An ideal bone substitute should be made of biocompatible materials that mimic the structure, characteristics, and functions of natural bone. Many researchers have worked on the fabrication of different bone scaffold systems including ceramic–polymer hybrid system. In the present study, we incorporated hyaluronic acid–gelatin hydrogel to micro-channeled biphasic calcium phosphate granules as a carrier to improve cell attachment and proliferation through highly interconnected porous structure. This hybrid system is composed of ceramic biphasic calcium phosphate granules measuring 1 mm in diameter with seven holes and hyaluronic acid–gelatin hydrogel. This combination of biphasic calcium phosphate and hyaluronic acid–gelatin retained suitable characteristics for bone regeneration. The resulting scaffold had a porosity of 56% with a suitable pore sizes. The mechanical strength of biphasic calcium phosphate granule increased after loading hyaluronic acid–gelatin from 4.26 ± 0.43 to 6.57 ± 0.25 MPa, which is highly recommended for cancellous bone substitution. Swelling and degradation rates decreased in the hybrid scaffold compared to hydrogel due to the presence of granules in hybrid scaffold. In vitro cytocompatibility studies were observed by preosteoblasts (MC3T3-E1) cell line and the result revealed that biphasic calcium phosphate/hyaluronic acid–gelatin significantly increased cell growth and proliferation compared to biphasic calcium phosphate granules. Analysis of micro-computed tomography data and stained tissue sections from the implanted samples showed that the hybrid scaffold had good osseointegration and better bone formation in the scaffold one and two months postimplantation. Histological section confirmed the formation of dense collagenous tissue and new bone in biphasic calcium phosphate/hyaluronic acid–gelatin scaffolds at two months. Our study demonstrated that such hybrid biphasic calcium phosphate/hyaluronic acid–gelatin scaffold is a promising system for bone regeneration.

In this study, a novel hybrid polyurethane/polycaprolactone (PU/PCL) tubular scaffold was fabricated using the electrospinning process for blood vessel prosthesis applications. The detailed microstructure and material properties such as porosity, tensile and bust strength, contact angle, and biocompatibility were investigated and compared with those of monolithic PU and PCL scaffolds. The mechanical properties of the hybrid PU/PCL scaffold (tensile strength: 18 MPa, pressure strength: 590 mmHg) were found to be within the range needed for artificial blood vessel applications. The pore sizes of the PU/PCL scaffold ranged from 5–150 um in diameter, are sufficient enough to allow nutrient diffusion across the membrane. The reduced hydrophobic property of the PU/PCL scaffold was the result of the addition of relatively less hydrophobic PU compared with monolithic PCL scaffold. The biocompatibility of the PU/PCL scaffold was evaluated through cytotoxicity testing, and morphological observation by scanning electron microscopy and confocal microscopy using cow pulmonary artery endothelial cells and fibroblast like cells (L929).

In this study, the optimized formulations of polycaprolactone (PCL) combined with poly(lactic-co-glycolic acid) (PLGA), gelatin (GEL), and biphasic calcium phosphate (BCP) were analyzed in terms of cytocompatibility with bone-related cells, hemocompatibility, and in vivo bone-regenerating capacity to determine their potentials for bone tissue regeneration. Fiber morphology of PCL/GEL and PCL/BCP electrospun mats considerably differs from that of the PCL membrane. Based on the contact angle analyses, the addition of GEL and PLGA was shown to reduce the hydrophobicity of these membranes. The assessment of in vitro cytocompatibility using MC3T3-E1 cells indicated that all of the membranes were suitable for pre-osteoblast proliferation and adhesion, with PCL/BCP having a significantly higher reading after seven days of incubation. The results of the in vitro hemocompatibility of the different fibrous scaffolds suggest that coagulation and platelet adhesion were higher for hydrophobic membranes (PCL and PCL/PLGA), while hemolysis can be associated with fiber morphology. The potential of the membranes for bone regeneration was determined by analyzing the microCT data and tissue sections of samples implanted in 5 mm sized defects (one and two months). Although all of the membranes were suitable for pre-osteoblast proliferation, in vivo bone regeneration after two months was found to be significantly higher in PCL/BCP (p < 0.001).