A comparative study of a rabbit spinal tuberculosis model constructed by local direct infection via the posterior lateral approach

The present study aims to establish a method of constructing a New Zealand rabbit spinal tuberculosis model by direct local infusion of M. tuberculosis H37Rv strain into the intervertebral disc space through the posterior lateral approach. Sixty-six New Zealand rabbits were pretreated with complete Freund's adjuvant and randomly divided into 4 group: the posterolateral approach model group (Group A, 25), ventral transverse process approach model group (Group B, 25), control group (Group C, 10), and blank group (Group D, 6). In Groups A and B, the bone holes were filled with gelatin sponge after drilling, and the local area was directly infused with 0.1 ml of M. tuberculosis H37Rv strain suspension. In Group C, the gelatin sponge was filled through the posterolateral approach and the local area was infused with 0.1 ml of normal saline suspension. In Group D, No specific treatment was performed. The general conditions of the experimental rabbits in each group were compared to those of a control group; the degree of vertebral body exposure, incision length, and complications of the two methods were compared; and the tuberculosis models were evaluated by imaging, histopathology, and bacterial culture. In Group A, the lateral side of the vertebral body was well exposed, the damage was mild, and no peritoneal rupture or gastrointestinal complications were observed. In Group B, the ventral side of the vertebral body and the intervertebral disc were exposed, and abdominal complications were more likely to occur. The survival rates of the experimental rabbits at 8 weeks after surgery were 92.0% in Group A, 88.00% in Group B, 90.0% in Group C, and 100% in Group D. MRI examinations showed that in Group A, the positive rate of radiographic bone findings was 86.9% at 4 weeks after surgery and 100% at 8 weeks after surgery; in Group B, the positive rate of radiographic bone findings was 78.2% at 4 weeks after surgery and 95.4% at 8 weeks after surgery. There was no significant difference between Groups A and B in the radiographic bone findings rate detected by the same imaging method at the same time point (P > 0.05). Eight weeks after surgery, bone destruction, paravertebral abscess, and caseous necrosis occurred in the vertebral bodies of surviving rabbits in Groups A and B. The BacT/ALERT 3D rapid culture system was used to culture the pus in the lesion, and the results showed that the positive rate of tuberculosis was 52.17% in Group A and 54.54% in Group B, and the difference was not statistically significant (P > 0.05). After pretreatment with complete Freund's adjuvant, direct infusion of the H37Rv strain of M. tuberculosis into the intervertebral disc space of New Zealand rabbits via the posterolateral approach and the ventral transverse process approach can successfully establish rabbit spinal tuberculosis models.

Preparation of Coralline Hydroxyapatite Implant with Recombinant Human Bone Morphogenetic Protein-2-Loaded Chitosan Nanospheres and Its Osteogenic Efficacy

OBJECTIVE

Spinal fusion is one of the most common surgical interventions for spine reconstruction. Despite the efforts to promote osteogenesis after spinal fusion, osteogenesis after spinal fusion remains a clinical challenge and new methods are still needed. The bone morphogenetic protein-2 (BMP-2) is a widely reported factor that can facilitate the osteogenesis in spinal fusion. In previous research, we found that the delivery of chitosan nanospheres could promote the effects of BMP-2 on osteogenic activity. The coralline hydroxyapatite (CHA) is one of the most frequently used implants in bone fusion. However, up to now no study has focused on the osteogenic efficacy of the CHA composite with recombinant human BMP-2 (rhBMP-2)-loaded chitosan nanospheres. This study aimed to investigate the effects of the CHA implant with rhBMP-2-loaded chitosan nanospheres on osteogenesis in spinal fusion.

METHODS

The rhBMP-2-loaded microspheres and CHA composite (rhBMP-2 microspheres/CHA) were prepared and were used for implantation of the rats. All SD rats were divided into four groups: the rhBMP-2 microspheres/CHA composite group (containing 0.5 mg rhBMP-2), the rhBMP-2-loaded CHA (rhBMP-2/CHA) composite group (containing 0.5 mg rhBMP-2), the blank CHA group, and the negative control group. The microsphere morphology was scanned and analyzed using a scanning electron microscope. Micro-computed tomography examination and three-dimensional reconstruction were performed 4 weeks after the surgery. Hematoxylin and eosin staining was conducted for histological analysis. Both alkaline phosphatase (ALP) and calcium content were measured.

RESULTS

The rhBMP-2-loaded CHA (rhBMP-2/CHA) composite was successfully prepared. Spherical regularity and a smooth and unwrinkled surface of the spheres were observed in all chitosan (CS)/rhBMP-2 microspheres. No side effects, infections, or abnormal behaviors were found in the animals. After 4 weeks of surgery, obvious new bone formation and bone fusion could be observed around the implant in both the rhBMP-2 microspheres/CHA composite group and the rhBMP-2/CHA composite group. No ectopic osteogenesis was found in the vertebral canal or other muscle tissues. After 4 weeks of implantation, in both the rhBMP-2 microspheres/CHA composite group and the rhBMP-2/CHA composite group, osteoid tissues could be found, and bone cells, bone marrow, and trabecular bone turned into mature sclerotin, obvious bone tissue formation could be also seen. Both ALP activity and calcium content in the rhBMP-2 microspheres/CHA composite group (6.52 ± 0.50 kat/g and 17.54 ± 2.49 μg/mg) were significantly higher than in all other groups.

CONCLUSION

The composite with rhBMP-2-loaded CS nanospheres could enhance osteogenic efficacy and increase the ALP activity and calcium content. These results might provide a novel method for osteogenesis in spinal fusion and offer new insight into the role of BMP-2 in osteogenesis.

Native Bovine Hydroxyapatite Powder, Demineralised Bone Matrix Powder, and Purified Bone Collagen Membranes Are Efficient in Repair of Critical-Sized Rat Calvarial Defects

Here we evaluated the efficacy of bone repair using various native bovine biomaterials (refined hydroxyapatite (HA), demineralised bone matrix (DBM), and purified bone collagen (COLL)) as compared with commercially available bone mineral and bone autografts. We employed a conventional critical-sized (8 mm diameter) rat calvarial defect model (6-month-old male Sprague–Dawley rats, n = 72 in total). The artificial defect was repaired using HA, DBM, COLL, commercially available bone mineral powder, bone calvarial autograft, or remained unfilled (n = 12 animals per group). Rats were euthanised 4 or 12 weeks postimplantation (n = 6 per time point) with the subsequent examination to assess the extent, volume, area, and mineral density of the repaired tissue by means of microcomputed tomography and hematoxylin and eosin staining. Bovine HA and DBM powder exhibited excellent repair capability similar to the autografts and commercially available bone mineral powder while COLL showed higher bone repair rate. We suggest that HA and DBM powder obtained from bovine bone tissue can be equally applied for the repair of bone defects and demonstrate sufficient potential to be implemented into clinical studies.

The effect of aging on posterior intertransverse lumbar fusion: a New Zealand white rabbit model

STUDY DESIGN

In vivo assessment of lumbar spinal fusion between a younger and older cohort of New Zealand white rabbits.

OBJECTIVE

Directly compare fusion within young and aged New Zealand white rabbits to establish an aged spinal fusion model translational research.

SUMMARY OF BACKGROUND DATA

Prior studies have utilized skeletally mature young rabbits (6-12 mo old) that may not be appropriate as an analog for studying the aging human spine.

METHODS

Ten aged (>36 mo old) and 10 young (12 mo old) New Zealand white rabbits underwent a single-level, bilateral, L5-6 posterolateral intertransverse fusion using autogenous iliac crest bone graft. The animals were killed at 6 weeks postoperatively, and the specimens were then evaluated with quantitative microcomputerized tomography and manual palpation by 6 orthopedic surgeons. The fusions were graded as either fused or not fused by each examiner. The spines were then embedded in poly(methyl methacrylate) and cut into 2-mm-thick sections for histologic analysis.

RESULTS

A higher percentage of young rabbits were determined to be successfully fused through manual palpation testing compared with the aged rabbits. Micro-computed tomography (CT) analysis revealed a significantly greater fusion mass volume in the younger rabbits than in the older cohort. In addition, the fusion density of the younger rabbits was found to be significantly lower than that of the older rabbits when normalized to the bone density in the nonfused portion of the spine. Histologic analysis showed that the quality of the bone within the fusion mass was consistent between the young and old rabbits. A greater number of young animals had bilateral continuous bone graft compared with the aged animals.

CONCLUSIONS

The aged (>36 mo) New Zealand white rabbit model appears to be a valid model to evaluate the effect of aging on lumbar fusion and has the potential to more accurately model conditions that are present in the older human spine.

Clinical application of cultured epithelial autografts on acellular dermal matrices in the treatment of extended burn injuries

Achieving permanent replacement of skin in extensive full-thickness and deep partial-thickness burn injuries and chronic wounds remains one of the fundamental surgical problems. Presently, split-thickness skin grafts are still considered the best material for surgical repair of an excised burn wound. However, in burns that affect greater than 50% of total body surface area, the patient has insufficient areas of unaffected skin from which split-thickness skin grafts can be harvested. The use of cultured epithelial (or epidermal) autografts (CEAs) has achieved satisfactory results. But the take rate of CEAs is poor in full-thickness bed or in chronically infected area. Providing temporary cover with allograft skin, or a more permanent allodermis, may increase clinical take. This review aims to (1) describe the use of CEAs in the regeneration of the epidermis, (2) introduce the application of the acellular dermal matrices (ADMs) in the clinics, and (3) enhance understanding of the CEAs applied with ADM as an appropriate strategy to treat the extended burn injuries. The current evidence regarding the cultured epithelial cell or keratinocyte autograft and dermal grafts applied in the treatment of burn injuries was investigated with an extensive electronic and manual search (MEDLINE and EMBASE). The included literature (N=136 publications) was critically evaluated focusing on the efficacy and safety of this technique in improving the healing of the deep dermal and full-thickness burn injuries. This review concluded that the use of ADM with CEAs is becoming increasingly routine, particularly as a life-saving tool after acute thermal trauma.

Multipotent adult progenitor cell-loaded demineralized bone matrix for bone tissue engineering

Multipotent adult progenitor cells (MAPCs) from bone marrow have been shown to be capable of forming bone, cartilage and other connective tissues. In addition, MAPCs differentiate into lineages that are different from their germ layers of origin. Previous studies showed the ability of MAPCs to improve cardiac function and control allogenic-reactive responses associated with acute graft versus host disease. In the current study, we evaluated the ability of MAPCs to produce bone matrix on demineralized bone allograft substrates. Specifically, MAPCs expressed alkaline phosphatase, produced extracellular matrix proteins and deposited calcium-containing mineral on demineralized bone matrices. Furthermore, the addition of MAPCs on demineralized bone matrix (DBM) scaffolds enhanced osteoinductivity of the carrier in a rat ectopic pouch model. These results demonstrated the potential of MAPCs as a new approach for bone repair in tissue-engineering applications.

The use of platelet rich plasma, bone morphogenetic protein-2 and different scaffolds in oral and maxillofacial surgery - literature review in comparison with own clinical experience

Objectives

The purpose of this article was to review and critically assess the use of platelet rich plasma, recombinant human bone morphogenetic protein-2 and different scaffolds (i.e. tricalciumphosphate, polycaprolactone, demineralized bone matrix and anorganic bovine bone mineral) in oral and maxillofacial surgery comparing the relevant literature and own clinical experience.

Material and Methods

A literature review was conducted using MEDLINE, MEDPILOT and COCHRANE DATABASE OF SYSTEMATIC REVIEWS. It concentrated on manuscripts and overviews published in the last five years (2006-2010). The key terms employed were platelet rich plasma, bone morphogenetic proteins and their combinations with the above mentioned scaffolds. The results of clinical studies and animal trials were especially emphasized. The statements from the literature were compared with authors’ own clinical data.

Results

New publications and overviews demonstrate the advantages of platelet rich plasma in bone regeneration. The results from the literature review were discussed and compared with the publications detailing authors' own experiences.

Conclusions

A favourable outcome concerning newly grown bone was achieved combining platelet rich plasma in addition to optimal matrices with or without recombinant human bone morphogenetic protein-2, depending on the clinical case. As a consequence, the paradigm shift from transplantation of autogenous bone to bone tissue engineering appears promising.

Long-term rabbits bone response to titanium implants in the presence of inorganic bovine-derived graft

This study evaluated bone responses to titanium implants in the presence of an inorganic graft material. The bilateral mandible incisors of 24 rabbits were surgically extracted and one of the exposed sockets, chosen at random, was filled with an inorganic xenogenic bone graft (Gen-ox®), whereas the remaining socket was left to heal naturally and served as a control. After 60 days, titanium implants were inserted in the specific areas, and on days 0, 30, 60, and 180 after the implant insertions, six animals of each group were killed. Digital periapical radiography of implant region was obtained and vertical bone height (VBH) and bone density (BD) were evaluated by digital analysis system. In the undecalcified tissue cuts, bone-to-implant contact (BIC) and bone area (BA) within the limits of the implant threads were evaluated and compared statistically by means of two-way ANOVA and Tukey's test (ρ < 0.05). No significant differences were detected in VBH and BA, either between groups or between different experimental intervals. The BD was significantly higher in the experimental group than in the control group in all the intervals tested, but there were no significant differences by interval. The BIC was statistically lower in the control group on day 0; however, a significant increase was observed on days 60 and 180 (ρ < 0.05). The use of an inorganic xenograft prior to insertion of a titanium implant did not interfere with the course of osseointegration.