In situ tissue engineering of canine skull with guided bone regeneration

Cranial bone regeneration is challenging, because flat bones, including the skull, are more difficult to regenerate than tubular bones. However, promotion of cranial bone regeneration would directly benefit patients, who would be spared cosmetic handicaps including postoperative facial deformities commonly associated with the current techniques of bone reconstruction. We studied cranial bone regeneration and confirmed that collagen-coated beta-tricalcium phosphate (b-TCP) is a suitable raw material for regeneration of cranial bone and that bone marrow-derived stromal cells (BSCs) have the potential to promote bone regeneration. However, excessive fibrous tissue intrusion into the regenerative site or dislocation of the bone substitute material occasionally interrupted bone regeneration. To avoid such problems, we next assessed calcium alginate (CA) membrane, which is useful for guided bone regeneration (GBR), to investigate whether this material maintains the bone regenerative space. CA membrane prevents excessive fibrous tissue intrusion and/or dislocation of a bone scaffold. However, we found that CA membrane did not always accelerate cranial bone regeneration. Our results demonstrated that a supplementary supply of vessels or regulatory factors from superficial structures may be indispensable in cranial bone regeneration.

The aim of this study was to regenerate high-quality cranial bone using tissue engineering techniques, with subsequent extension to clinical application. Our previous study with a 3-month observation period indicated that a composite scaffold composed primarily of beta-tricalcium phosphate (TCP) had the potential for cranial bone regeneration. In this study, we investigated whether bone marrow derived stromal cells (BSCs) could promote the regeneration of cranial bone as determined after 3 and 6 months. The pilot study was conducted with 14 adult beagle dogs. Craniotomy was performed in the same manner used clinically. The bone defect (2 x 2 cm) was created at each canine temporoparietal region. The test animals were divided into three groups. In group I, the bone defect was closed by replacing the original free bone flap without filling the residual gaps. In group II, the gap was filled with a composite scaffold consisting of collagen coated beta-TCP and autologous bone fragments with fibrin glue. In group III, autologous cultured BSCs and the composite scaffold were used to fill the gap. The sites of craniotomy were analyzed with three-dimensional computed tomography and histologic examination 3 and 6 months after the operation. Bone regeneration was observed in groups II and III, with more extensive formation in group III than in group II. In group I, bone regeneration was not observed. This study showed that BSCs have the potential to promote cranial bone regeneration and confirmed the efficacy of a composite scaffold made of beta-TCP and autologous bone fragments with fibrin glue.

Bioremediation of oily seawater by Bacteria immobilization on a novel carrier material containing nutrients

Biofunctionalization of synthetic bone substitutes with angiogenic stem cells: Influence on regeneration of critical-size bone defects in an in vivo murine model

Introduction: This case report describes a synthetic polyethylene glycol (PEG) hydrogel membrane used to obtain guided bone regeneration (GBR) in a clinical case of a non‐submerged implant placement. The conditioning of this hydrogel membrane for bone regeneration is an innovation compared to previously used membranes in which the size and shape are already predetermined.Case Presentation: Eight weeks after a connective tissue graft on the maxillary lateral incisor of a 20‐year‐old female, tooth extraction and immediate implant placement were performed using a GBR technique with a PEG hydrogel membrane over a bone substitute material. The absence of inflammation and the good soft‐tissue healing confirmed the biocompatibility of the membrane. A three‐dimensional scan was taken to assess the behavior of the bone substitute covered with the PEG hydrogel membrane at 6 months after surgery.Conclusions: The synthetic PEG bone regeneration membrane presented in this case report differs from all other membranes by its hydrogel form. Its properties as described here make this membrane a new tool for clinicians and a source for additional clinical studies to analyze its characteristics in the various indications for GBR.

Stimulation of calvarial bone healing with human bone marrow stromal cells versus inhibition with adipose-tissue stromal cells on nanostructured β-TCP-collagen

Introduction: Soft tissue engineering strategies targeting volume loss restoration has been developed as the current management of soft tissue defects. Important components of this method are cell sources, scaffold, and bioreactor. Adipose-derived mesenchymal stem cell (ADMSC) from a stromal vascular fraction (SVF) attached to scaffold and differentiated into defect tissue through cell communication. This study was aimed to investigate the viability of ADMSC from SVF combined with collagen, calcium alginate, oxidized cellulose, gelatin, and amnion membrane in vitro. Method: This true experimental done in the laboratory using 24 samples of SVF ADMSC that had been cryopreserved for 5 months and already get through the thawing process. Result: Based on the descriptive analysis with 4 repetition each group and control, gelatin shows average 90.928 and deviation standard 1,053, oxidized cellulose average 19,528 and deviation standard 2,543, collagen average 93,273 and deviation standard 1,195, calcium alginate average 92,953 and deviation standard 1,257, amnion membrane average 92,068 and deviation standard 2,467, control 95,995 and deviation standard 0,428. Conclusion: The use of gelatin, collagen, calcium alginate, and amnion membrane as scaffold show high viability results of ADMSC from SVF. Otherwise, oxidized cellulose scaffold has the lowest amount of viable cell. However, the most recommended scaffold material is amnion membrane because of the easiness of the production process, high availability, high potency of cell growth, and low cost.

Selective diffusion of glucose, maltose, and raffinose through calcium alginate membranes characterized by a mass fraction of guluronate

Membrane permeation-controlled transdermal delivery devices for the controlled delivery of methylephedrine HCl were developed using calcium alginate membrane as ratecontrolling membrane. To increase the solubility of methylephedrine HCl in the systems, HPMC and agar binary gel was used as drug reservoir. In vitro drug release studies were carried out using modified Franz diffusion cells. The result shows that the step of drug penetrating through the calcium alginate membrane is rate-limiting, then the rate of drug release from the patch is considered to be membrane controlled. The release kinetics of ointment and patch may be square root time dependent and the highest regression coefficient was obtained with the Higuchi model. The surface permeability of ointment was reduced by crosslinking of the membranes and enable drug continuous release over prolonged periods. Above results will be helpful to possible development of rate-controlling membrane transdermal delivery systems for the other drugs.

The present in vivo study analyses both the inflammatory tissue reactions and the bone healing capacity of a newly developed bone substitute material (BSM) based on xenogeneic bone substitute granules combined with hyaluronate (HY) as a water-binding molecule. The results of the hyaluronate containing bone substitute material (BSM) were compared to a control xenogeneic BSM of the same chemical composition and a sham operation group up to 16 weeks post implantationem. A major focus of the study was to analyze the residual hyaluronate and its effects on the material-dependent healing behavior and the inflammatory tissue responses. The study included 63 male Wistar rats using the calvaria implantation model for 2, 8, and 16 weeks post implantationem. Established and Good Laboratory Practice (GLP)-conforming histological, histopathological, and histomorphometrical analysis methods were conducted. The results showed that the new hyaluronate containing BSM was gradually integrated within newly formed bone up to the end of the study that ended in a condition of complete bone defect healing. Thereby, no differences to the healing capacity of the control BSM were found. However, the bone formation in both groups was continuously significantly higher compared to the sham operation group. Additionally, no differences in the (inflammatory) tissue response that was analyzed via qualitative and (semi-) quantitative methods were found. Interestingly, no differences were found between the numbers of pro- and anti-inflammatory macrophages between the three study groups over the entire course of the study. No signs of the HY as a water-binding part of the BSM were histologically detectable at any of the study time points, altogether the results of the present study show that HY allows for an optimal material-associated bone tissue healing comparable to the control xenogeneic BSM. The added HY seems to be degraded within a very short time period of less than 2 weeks so that the remaining BSM granules allow for a gradual osteoconductive bone regeneration. Additionally, no differences between the inflammatory tissue reactions in both material groups and the sham operation group were found. Thus, the new hyaluronate containing xenogeneic BSM and also the control BSM have been shown to be fully biocompatible without any differences regarding bone regeneration.

Background and Objectives: he treatment of large bone defects in geriatric patients often presents a major surgical challenge because of age-related bone loss. In such patients, the scarcity of healthy makes autologous grafting techniques hard to perform. On the one hand, clinicians’ fear of possible infections limits using bone substitute materials (BSM). On the other hand, BSM is limitless and spares patients another surgery to harvest autologous material. Materials and Methods: To address the aptness of BSM in geriatric patients, we performed a retrospective analysis of all patients over the age of 64 years who visited our clinic between the years 2011–2018. The study assessed postoperative complications clinically and healing results radiologically. The study included 83 patients with bone defects at the distal radius, proximal humerus, and proximal tibia. The defect zones were filled with BSM based on either nanocrystalline hydroxyapatite (NHA) or calcium phosphate (CP). For comparison, a reference group (empty defect, ED) without the void filling with a BSM was also included. Results: 106 patients sustained traumatic fractures of the distal radius (71.7%), proximal humerus (5.7%), and proximal tibia (22.6%). No difference was found between the BSM groups in infection occurrence (p = 1.0). Although not statistically significant, the BSM groups showed a lower rate of pseudarthrosis (p = 0.09) compared with the ED group. Relative risk (RR) of complications was 32.64% less in the BSM groups compared with the ED group. The additional beneficial outcome of BSM was demonstrated by calculating the number needed to treat (NNT). The calculation showed that with every six patients treated, at least one complication could be avoided. Radiological assessment of bone healing showed significant improvement in the bridging of the defect zone (p < 0.001) when BSM was used. Conclusions: In contrast to previous studies, the study showed that BSM could support bone healing and does not present an infection risk in geriatric patients. The NNT calculation indicates a wider potential benefit of BSM.

Third molar extraction is a common oral surgical procedure that can be accompanied by challenges in wound healing and bone regeneration. Materials such as bone substitute materials (BSMs) and platelet-rich fibrin (PRF) are often used to support socket regeneration. This prospective randomized controlled split-mouth clinical trial compared PRF application combined with BSM versus PRF alone in patients requiring bilateral third molar extraction. A total of 15 patients underwent standardized osteotomy procedures, with sockets filled either with PRF alone (control group) or with BSM + PRF on opposite sides (test group) under general anesthesia and with patients blinded to the treatment allocation. Postoperative pain and swelling were measured over 7 days using a visual analog scale and anatomical distance measurements, respectively. Bone regeneration was evaluated using cone beam computed tomography (CBCT) scans after an average healing period of six months, with results showing no significant differences between groups in terms of postoperative pain or swelling (n = 12; 3 patients were lost to randomization). However, CBCT imaging revealed covered socket residuum (CSR)—non-mineralized areas within the socket—in the PRF only group, whereas the BSM + PRF group demonstrated more homogeneous and mineralized bone formation throughout the extraction sites (n = 8; 5 patients were lost to follow-up). These non-mineralized areas represent covered socket residuum within the extraction sockets, which poses a clinical risk of infection and may negatively affect the dental health of the adjacent second molar. Based on the presented findings, we recommend combining BSM with PRF to support bone regeneration and regulate the postoperative pain and swelling following third molar extraction. Nevertheless, further research is required to determine the most suitable BSM type in this regard.

Porous zirconia/hydroxyapatite scaffolds for bone reconstruction

ABSTRACTIn order to control the drug release from coated hydrogels by preventing membrane fractures, an intramembrane freely swellable matrix device was designed by enclosing a void space between a crosslinkedpoly(vinyl alcohol) (PVA) matrix and a calcium alginate membrane. The highly swellable PVA matrix loaded with diltiazem hydrochloride was obtained by means of a simplified procedure of the polymer crosslinking reaction using glutaraldehyde in solution with ammonium persulfate. The undried swollen matrix was coated with a calcium alginate membrane employing an ionotropic gelation of sodium alginate induced by calcium ions. The subsequent drying process generated a void space separating the inner core from the membrane. The resulting calcium alginate membrane, which was uniform and compact in the structure, increased in thickness according to the coating time. Coating times exceeding 5 min allowed modification of the drug release profile providing, after a short burst period, sustained and constant rate phases in both simulated gastric fluid and simulated intestinal fluid. Because the inner hydrogel expanded freely inside the device, the unstressed and intact membrane could act as the rate-controlling factor in the drug release process. Owing to the pH-dependent behavior of the membrane, most of the drug was delivered in intestinal fluid. Therefore, the device proposed could be advantageously used for drug targeting to the small intestine.

Bone regeneration for large, critical-sized bone defects remains a clinical challenge nowadays. Guided bone regeneration (GBR) is a promising technique for the repair of multiple bone defects, which is widely used in oral and maxillofacial bone defects but is still unsatisfied in the treatment of long bone defects. Here, we successfully fabricated a bilayer mineralized collagen/collagen (MC/Col)-GBR membrane with excellent osteoinductive and barrier function by coating the MC particles prepared via in situ biomimetic mineralization process on one side of a sheet-like pure collagen layer. The aim of the present study was to investigate the physicochemical properties and biological functions of the MC/Col film, and to further evaluate its bone regeneration efficiency in large bone defect repair. Fourier-transform infrared spectra and X-ray diffraction patterns confirmed the presence of both hydroxyapatite and collagen phase in the MC/Col film, as well as the chemical interaction between them. stereo microscope, scanning electron microscopy and atomic force microscope showed the uniform distribution of MC particles in the MC/Col film, resulting in a rougher surface compared to the pure Col film. The quantitative analysis of surface contact angle, light transmittance and tensile strength demonstrated that the MC/Col film have better hydrophilicity, mechanical properties, light-barrier properties, respectively. In vitro macrophage co-culture experiments showed that the MC/Col film can effectively inhibit macrophage proliferation and fusion, reducing fibrous capsule formation. In vivo bone repair assessment of a rabbit critical segmental radial defect proved that the MC/Col film performed better than other groups in promoting bone repair and regeneration due to their unique dual osteoinductive/barrier function. These findings provided evidence that MC/Col film has a great clinical potential for effective bone defect repair.Graphic abstract