Polyurethane foam/nano hydroxyapatite composite as a suitable scaffold for bone tissue regeneration.

In bone tissue regeneration, the use of biomineralized scaffolds to create the 3D porous structure needed for well-fitting with defect size and appropriate cell interactions, is a promising alternative to autologous and heterologous bone grafts. Biomineralized polyurethane (PU) foams are here investigated as scaffold for bone tissue regeneration. Biomineralization of the foams was carried out by activation of PU surface by a two steps procedure performed for different times (1 to 4 weeks). Scaffolds were investigated for morphological, chemico-physical and mechanical properties, as well as for in vitro interaction with rat Bone Marrow Mesenchymal Stem Cells (BMSCs). Untreated and biomineralized PU samples showed a homogenous morphology and regular pore size (average Ø=407µm). Phase and structure of formed calcium phosphates (CaPs) layer onto the PU foam were analyzed by Fourier Transform Infrared spectroscopy and X-ray diffraction, proving the formation of bone-like nano hydroxyapatite. Biomineralization caused a significant increase of mechanical properties of treated foams compared to untreated ones. Biomineralization also affected the PU scaffold cytocompatibility providing a more appropriate surface for cell attachment and proliferation. Considering the obtained results, the proposed scaffold can be considered suitable for bone tissue regeneration.

Porous crosslinked poly(ε-caprolactone fumarate)/nanohydroxyapatite composites for bone tissue engineering.

Porous nanocomposites based on poly(ε-caprolactone fumarate) (PCLF) resin matrix; N-vinyl pyrrolidone (NVP) as a reactive diluents and nanohydroxyapatite (nHA) filler were developed for bone tissue engineering applications. Nanocomposite scaffolds with three different contents of nHA [5, 10, and 20 (w/w %)] were prepared by thermal crosslinking of PCLF followed by particulate leaching and characterized in terms of mechanical properties (cyclic loading) and in vitro cell-material interaction by MTT assay and alkaline phosphatase activity measurements. Five osteoblastic cell lines were used to investigate the ability of the nanocomposites to support cell attachment, spreading, and proliferation after 3, 7, and 14 days. By adding the nHA filler phase, elastic modulus of the nanocomposites increased significantly. Scaffolds showed comparable biocompatibility to neat nHA particles, commercial bone graft (Bio-Oss) and tissue culture polystyrene as control groups. According to the results it can be concluded that these scaffolds are potential candidates for bone substitution because of their mechanical strength and bioactivity.

Biocompatibility evaluation of HDPE-UHMWPE reinforced ß-TCP nanocomposites using highly purified human osteoblast cells.

Biocompatibility of ß-TCP/HDPE-UHMWPE nanocomposite as a new bone substitute material was evaluated by using highly purified human osteoblast cells. Human osteoblast cells were isolated from bone tissue and characterized by immunofluorescence Staining before and after purification using magnetic bead system. Moreover, proliferation, alkaline phosphatase production, cell attachment, calcium deposition, gene expression, and morphology of osteoblast cells on ß-TCP/HDPE-UHMWPE nanocomposites were evaluated. The results have shown that the human osteoblast cells were successfully purified and were suitable for subsequent cell culturing process. The high proliferation rate of osteoblast cells on ß-TCP/HDPE-UHMWPE nanocomposite confirmed the great biocompatibility of the scaffold. Expression of bone-specific genes was taken place after the cells were incubated in composite extract solutions. Furthermore, osteoblast cells were able to mineralize the matrix next to composite samples. Scanning electron microscopy demonstrated that cells had normal morphology on the scaffold. Thus, these results indicated that the nanosized ß-TCP/HDPE-UHMWPE blend composites could be potential scaffold, which is used in bone tissue engineering.

Prognostic factors in the occurrence of posttraumatic epilepsy after penetrating head injury suffered during military service.

In this retrospective study, the authors evaluated confounding risk factors, which are allegedly influential in causing unprovoked posttraumatic epilepsy, in 489 patients from the frontlines of the Iran-Iraq War. Four hundred eighty-nine patients were followed for 6 to154 months (mean 39.4 months, median 23 months), and important factors precipitating posttraumatic epilepsy were evaluated using uni- and multivariate regression analysis. One hundred fifty-seven (32%) of 489 patients became epileptic during the study period. The results of univariate analysis indicated a significant relationship between epilepsy and Glasgow Outcome Scale (GOS) score (X2 = 76.49, p < 0.0001, df = 2), Glasgow Coma Scale score at admission (X2 = 19.48, p < 0.0001, df = 3), motor deficit (X2 = 11.79, p < 0.001, df = 1), mode of injury (X2 = 10.731, p < 0.05), transventricular injury (X2 = 6.9, p < 0.008, df = 1), dysphasia (X2 = 5.3, p < 0.02), central nervous system infections (X2 = 5.3, p < 0.02), and early-onset seizures (X2 = 4.1, p < 0.04, df = 1). The results of multivariate analysis, on the other hand, indicated that the GOS score and motor deficit were of greater statistical importance (X2 = 35.24, p < 0.0001; and X2 = 7.1, p < 0.07, respectively). Factors that did have much statistically significant bearing on posttraumatic epilepsy were the projectile type, site of injury on the skull, patient age, number of affected lobes, related hemorrhagic complications, and retained metallic or bone fragments. Glasgow Outcome Scale score and focal motor neurological deficit are of particular importance in predicting posttraumatic epilepsy after missile head injury.