Bone transplantation

Development of an injectable chitosan-based hydrogel containing nano-hydroxy-apatite and alendronate for MSC-based therapy

BACKGROUND

The combination of cells and biomaterials has become a powerful approach to regenerative medicine in recent years. Understanding the in-vitro interactions between cells and biomaterials is crucial for the success of regenerative medicine.

AIM

In this study, we developed an AD-pectin/chitosan/nano-crystalline cellulose scaffold with nano-hydroxy-apatite (n-HAP) and alendronate (ALN). The second step was to evaluate its effect on the immunomodulatory properties and biological behaviors of seeded adipose-derived mesenchymal stem cells (ADSCs) for bone tissue repair.

MATERIAL AND METHOD

After preparing and evaluating the characterization tests of the new combined n-HAP scaffold, we established different culture conditions to evaluate ADSC growth on this scaffold with or without ALN. The main assays were MTT assay, RT-PCR, and ELISA.

RESULTS

Our data regarding characterization tests (including SEM, TGA, FTIR, gelation time, swelling ratio, rheology and degradation tests) of ALN-loaded n-HAP scaffold showed the proper stability and good mechanical status of the scaffold. ADSC proliferation and viability increased in the presence of the scaffold compared with other conditions. Moreover, our data demonstrated increased gene expression and protein levels of anti-inflammatory TGF-β, HGF, and IDO cytokines in the presence of the ALN-loaded n-HAP scaffold, indicating the increased immunosuppressive activity of ADSCs in vitro.

CONCLUSION

This study demonstrates the promising abilities of the ALN-loaded n-HAP scaffold to increase the proliferation, viability, and immunomodulatory capacity of ADSCs, elucidating new aspects of cell-material interactions that can be used for bone tissue regeneration/repair, and paving the path of future research in developing new approaches for MSC- based therapy.

Bone graft tuberculosis outbreak in USA: Is it a concern in India?

Globally, 25% of the population is infected with tuberculosis, which poses a leading cause of death worldwide. The transmission of tuberculosis (TB) during organ transplant is reported in the literature whereas only one report has been published on the transmission of TB, during bone allograft transplantation. In the US, in May 2021, an outbreak of TB occurred in patients undergoing spine surgery with bone allograft. This bone graft was retrieved from 80 years deceased donor with latent TB, which was not diagnosed earlier. The recipients were started with a long course of anti-tuberculous drugs. This review narrates the pathway of TB spread among transplant recipients and the strategies to be followed while performing organ or tissue transplantation.

Application of the Fibrous Autograft in Posttraumatic Bone Regeneration of the Lower Jaw

The search for new types of bone substitutes is one of the topical problems of biology and medicine. The paper considered the role of fibrous autograft in reparative bone regeneration in the rat’s lower jaw model. Thirty Wistar rats were taken in the experiment: 15 in the experimental and 15 in the control group. Fibrous autograft was formed on the cellophane basis under the skin on the back of rats. Injury in the lower jaw with a diameter of 2 mm was formed and a fibrous graft was placed in injuries in the experimental group. Five animals from each groups were sacrificed at the first, third and fifth weeks of the experiment. The object of the further research was the samples of the lower jaws stained according to Van Gieson. Histological examination of the bone defect of the experimental group after 1 week showed absence of bone fragments and formation of fibrous callosity in the trauma zone. Further study of regenerate at the 3rd and the 5th weeks showed accelerated bone wound healing in the experimental group (compared to the control group). Thus, the autograft stimulates the process of bone tissue restoration in the area of the defect of the lower jaw model.

Time-dependent changes in dynamic mechanical properties of irradiated bone

The increased use of allograft tissue for musculoskeletal repair has brought more focus to the safety of allogenic tissue and the efficacy of various sterilization techniques. The currently available literature contains few examples of studies on long-lasting strains of bones but no example for irradiated bones. In this study the bovine femurs from a 2-year-old animal were machine cut and irradiated with the doses of 10, 15, 25, 35, 45 and 50 kGy. The dynamic mechanical analysis was performed at 1 Hz at the room temperature in a 3-point bending configuration for 2880 minutes. The final values of E' and E″ were dose independent but they were reached at different periods. For this reason, so called "critical point" was introduced for the further analysis. All the examined sample groups were characterized by statistically significant lower values of the critical point in comparison with the control samples (p<0.05) but the biggest differences were observed between the control samples and the samples irradiated with the doses of 10, 15 and 25 kGy. Current results and literature review suggest that the dose of 35 kGy is the optimal dose for ionizing radiation sterilization.

Attaining tibiofibular union using an inter-tibiofibular autograft. A series of 43 cases

INTRODUCTION

This study consisted of a series of 43 patients with lower leg non-union that were treated with an inter-tibiofibular autograft (ITFG).

MATERIAL AND METHODS

After reviewing the surgical technique, the overall theory behind the treatment is described, including stabilization, soft tissue repair, infection control if necessary and then performing a procedure to help achieve bone union.

RESULTS

After an average follow-up of 2 years, all the patients achieved union, but some required additional procedures. Only one patient had a delayed reactivation of the infection, which was successfully treated.

CONCLUSION

A broad set of indications for ITFG are proposed for lower leg non-union cases, in particular non-infected cases.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Effects of 20% demineralization on surface physical properties of compact bone scaffold and bone remodeling response at interface after orthotopic implantation

To enhance osteointegration with preservation of mechanical strength, a surface modification technique using 20% surface demineralization in a controlled manner was applied to custom-built cylindrical bio-derived compact bones (20% surface-demineralized cylindrical compact bio-derived bone scaffold: SDCBS); an undemineralized version was the control. The micro-surface topography of the two types of bone scaffolds was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). 20% demineralization led to significant increases in surface roughness (38.19%, P=0.001) and surface area (15.1%, P=0.030), compared with the control group's, while the decrease in mechanical properties was not statistically significant. Results of orthotopic implantation for 9 months demonstrated that 20% surface demineralization caused significantly rapid and homogeneous bone remodeling at the interface compared to control and led to a significantly rapid osteointegration of SDCBS with the host bone at the early and intermediate stages of osteointegration. The study indicates the potential of SDCBS in repairing clinical bone defects, and would help direct the use of various processes of biomaterials to support defect repairs within osseous sites.

Fibula and tibia fusion with cancellous allograft vitalised with autologous bone marrow: first results for infected tibial non-union

BACKGROUND AND AIMS

Autogenous bone grafting has been used in reconstructing bone defects and in stimulating fracture healing, producing high healing rates in the treatment of infected tibial non-unions. A novel therapeutic alternative is now available known as "vitalised allograft", a cancellous bone graft procured from femoral heads from living human donors and "vitalised" through the injection of autologous bone marrow. The aim of this study is to summarise the initial results of the fibula and tibia fusion using vitalised cancellous allograft in the treatment of infected tibial non-unions.

PATIENTS AND METHODS

We initiated a follow-up of 15 prospective non-randomized patients who received a vitalised allograft in the treatment of infected tibial non-unions in order to produce bony union. The patients included 13 men and 2 women with an average age of 48 years. All patients received a multi-stage surgical approach. After establishing an infection-free environment, allogenic cancellous bone grafting was performed, intended as the final surgical procedure in fibula and tibia fusion. Our follow-up included a clinical and radiographic investigation of the calf in four planes. We analysed union-rate and time required for bony consolidation, as well as recurrent infections, re-fractures, potential graft-resorption, and time needed for graft and bone remodelling.

RESULTS

With an average follow-up of 17.1 months, infection control was obtained in 14 of 15 patients, producing an infection arrest rate of 93.3%. Radiographs indicated consolidation in 11 out of 15 cases, with a union rate of 73.3%. Bone union was achieved on average in 17.1 weeks.

CONCLUSIONS

Fibula and tibia fusion with allogenic cancellous bone grafting, vitalised through autogenic bone marrow, could well become an innovative treatment option for infected tibial non-unions. We need, however, to analyse a higher number of cases over a longer follow-up period in order to assess more accurately recurrent infections and re-fractures.

Bioengineered human bone tissue using autogenous osteoblasts cultured on different biomatrices

Surgical treatment of critical-size posttraumatic bone defects is still a challenging problem, even in modern bone and joint surgery. Progress in cellular and molecular biology during the last decade now permits novel approaches in bone engineering. Recent conceptual and technical advances have enabled the use of mitotically expanded, bone-derived cells as a therapeutic approach for tissue repair. Using three different tissue carrier systems, we successfully cultivated human osteoblasts in a newly developed perfusion chamber. We studied cell proliferation and the expression of osteocalcin, osteopontin, bone morphogenetic protein-2A, alkaline phosphatase, and vascular endothelial growth factor as parameters for osteoblast function and viability. Adherence of highly enriched human osteoblasts had already started after 1 h and resulted in completely overgrown human bone pieces after 10 days. Expression analysis of bone-specific alkaline phosphatase indicated differentiating osteoblasts, whereas the high mRNA expression of osteocalcin and osteopontin revealed terminally differentiated osteoblasts and the process of mineralization. Additionally, gene expression was significantly higher when demineralized bone was used as biomatrix, compared to autoclaved bone and hydroxyapatite ceramics. We conclude that with our newly developed perfusion culture system, vital autogenous bone implants of clinically applicable size can be generated within 17 days in order to manage critical-size bone defects.

Effect of gas-plasma sterilization on the osteoinductive capacity of demineralized bone matrix

The current study evaluated the effect of low-temperature hydrogen peroxide gas plasma sterilization on the osteoinductive capability of human demineralized bone matrix using a rat model. Twelve athymic rats received three separate implants consisting of steam-sterilized demineralized bone matrix (negative control), sterile-harvest demineralized bone matrix (positive control), and gas-plasma-sterilized demineralized bone matrix. A demineralized bone matrix pellet from each sterilization group was placed individually into one of three separate soft tissue pockets created in the epaxial musculature of each rat. All 12 rats were euthanized 9 weeks after implantation. Each implantation site was removed along with 0.5-cm normal tissue around the implant. Histologic examination was done on each implant site to determine the presence or absence of new bone, cartilage, or bone marrow elements. All 12 sterile harvest demineralized bone matrix sites histologically contained new bone elements, whereas none of the negative control or gas plasma sterilized demineralized bone matrix sites contained any of these same elements. The results of this study indicate that demineralized bone matrix sterilized with low-temperature, gas-plasma sterilization loses its osteoinductive capacity in a manner similar to that of steam-sterilized demineralized bone matrix, making low-temperature, gas- plasma sterilization unsuitable as a method of secondary sterilization of demineralized bone matrix.

Effect of intramedullary polymethylmethacrylate and autogenous cancellous bone on healing of frozen segmental allografts

This study was designed to compare bone mineral density, periosteal callus production, new bone formation, bone porosity, histologic appearance, and union of mid-diaphyseal segmental allografts of the femur stabilized with an interlocking nail technique in a canine model 6 months after the procedure. An in vivo study was performed to compare the effects of augmenting interlocking nail fixation with an interlocking nail alone, intramedullary polymethylmethacrylate, intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface of the host-allograft junction, autogenous cancellous bone applied to the endosteal surface of the allograft, autogenous cancellous bone applied to the periosteal surface of the host-allograft junction, and autogenous cancellous bone applied to the periosteal surface of the host-allograft junction and to the endosteal surface of the allograft. There were no differences among treatments for bone mineral density at any time interval. Callus area 4 weeks after the procedure was greater along the lateral and cranial surfaces for treatments with periosteal cancellous bone (p < 0.05). New bone within the allograft segment did not differ among treatments and was reduced compared with the host-allograft junctions (p < 0.05). The amount and quality of bone tissue at the host-allograft junctions were greatest with treatments of intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface of the host-allograft junction and of autogenous cancellous bone applied to the periosteal surface of the host-allograft junction and to the endosteal surface of the allograft (p < 0.05). The rate of bone union was lower, and there was a greater gap (non-bone tissue) remaining between host and allograft bone with treatment involving just intramedullary polymethylmethacrylate than with other treatments (p < 0.05). The results suggest that augmenting interlocking nail fixation with intramedullary polymethylmethacrylate by itself offers no advantage but that a combination of intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface or of cancellous bone within the medullary canal and at the periosteal surface improves the quality of healing at 6 months.

In vitro and in vivo study on the effect of autogenous cancellous bone and intramedullary polymethylmethacrylate on allograft construct strength

An in vitro study was performed to compare the effects of augmenting interlocking nails of one of two diameters (5 or 6 mm) with intramedullary polymethylmethacrylate. Subsequently, an in vivo study was performed to compare the effects of augmenting the interlocking nail with five combinations of intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface or within the medullary canal. Dogs were killed 6 months after the procedure for biomechanical evaluation of the femora in axial compression, mediolateral and craniocaudal bending, and torsion. Results from the in vitro study at the proximal osteotomy indicated the 6-mm interlocking nail with intramedullary polymethylmethacrylate had greater stiffness than the 5-mm interlocking nail without it (p < 0.05). At the distal osteotomy, regardless of the diameter of the interlocking nail, the addition of intramedullary polymethylmethacrylate increased stiffness (p < 0.05). Results from the in vivo study indicated greater global construct stiffness with an interlocking nail alone, an interlocking nail augmented with intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface, and an interlocking nail augmented with cancellous bone within the medullary canal and at the periosteal surface (p < 0.05). At the osteotomy level, the interlocking nail augmented with intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface had greater stiffness than did an interlocking nail alone or an interlocking nail augmented with either intramedullary polymethylmethacrylate, cancellous bone within the medullary canal, or cancellous bone at the periosteal surface (p < 0.05) but produced the same results as an interlocking nail augmented with cancellous bone within the medullary canal and at the periosteal surface. The results suggest that augmenting interlocking nail fixation with intramedullary polymethylmethacrylate by itself offers no advantage but that a combination of intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface improves structural properties at 6 months.

Regenerative response to membranous and enchondral lyophilized allogeneic bone in rabbit skull defects

The regenerative responses of inlays of lyophilized allogeneic bone of membranous (skull) and enchondral (tibia) origin were studied in an experimental cranioplasty model in rabbits. The lyophilized bone particles were also bioassayed for inductive bone production in an orthotopic critical size defect rat model. Three trephined calvarial defects were evaluated in each of 14 adult rabbits. The experimental materials were implanted into two of the defects and the third was left empty for control purposes. The implants disclosed no major structural divergences as assessed by scanning electron microscopy. Healing was evaluated by light microscopy and contact radiography after periods of four and 15 weeks. The lyophilized bone allografts of both embryonic origins displayed a similar fashion of bone regeneration, bone marrow reappearance, and volumetric density of trabecular bone substance and displayed no obvious differences between experimental groups or intervals. The two materials exhibited low osteoinductive potential.