Long-term feasibility and biocompatibility of directly microsurgically implanted intrafascicular electrodes in free roaming rabbits.

Novel neural interfaces capable of reliably capturing electrical signals are crucial for the development of prostheses. Longitudinal intrafascicular electrodes (LIFEs) have been proposed as a promising technology, and their feasibility and biocompatibility need to be investigated for long-term implantation. In this study, custom-designed 95%Pt-5%Ir intrafascicular electrodes were implanted into the sciatic nerves of 14 rabbits using our novel direct microsurgical technique. The biocompatibility and their ability to record electrophysiological signals were serially investigated up to 9 months after implantation. Nerve tissues were examined using light and transmitted electron microscopy, and axon diameters were quantified, evaluated over time, and compared with sham-control (N = 4). Selective stimulation and stable recording properties of electrical signals were achieved by intrafascicular electrodes along the experimental period. While electrophysiological signal amplitude decreased by as early as 1 month after implantation (p < 0.05), the signal strength recovered to baseline levels by 3-5 months (p > 0.05). Axon diameter results showed a similar trend of initial decline (10.8% reduction, p < 0.01) followed by gradual recovery by 6 months (p > 0.05). Microstructural and ultrastructural analysis revealed modest tissue damage at the implantation site after implantation with gradual normalization over time. Intrafascicular electrodes implanted with direct microsurgical techniques demonstrated good biocompatibility and have great potential for long-term implantation and electrophysiological recordings. Though subtle tissue damage impaired ability to capture electrophysiological signals in the first 2 months, this damage gradually normalized after 3 months, and was fully normalized by 6 months. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 435-444, 2019.

Expression of Livin and PlGF in human osteosarcoma is associated with tumor progression and clinical outcome.

Baculoviral IAP repeat containing 7 (BIRC7/Livin/ML-IAP/KIAP; referred to as Livin throughout the present study) and placental growth factor (PlGF) are not detectable in the majority of normal differentiated tissues, but are present in a number of types of cancer, including hepatocellular carcinoma, ovarian cancer and renal cell carcinoma. The aim of the present study was to assess the expression levels of Livin and PlGF in human osteosarcoma specimens and cell lines, and to analyze the functions of Livin and PIGF in the prognosis of osteosarcoma. The expression levels of Livin and PlGF in 48 osteosarcoma specimens and three osteosarcoma cells were determined using immunohistochemistry and reverse transcription-quantitative polymerase chain reaction. The positivity rates of Livin and PlGF in osteosarcoma specimens were 58.3 and 60.4%, respectively, but were 0% in normal bone tissues. The expression levels of Livin and PlGF were increased in MG-63 cells, compared with those in the other cell lines evaluated in the present study. In addition, the expression levels of Livin and PlGF were significantly associated with tumor diameter and Enneking staging, but were independent of tumor site, age and sex of patients. The expression level of Livin was not associated with PlGF. Furthermore, the 5-year overall survival rate was decreased in the Livin or PlGF expression group, compared with that in the non-expression group (P=0.034 and P=0.012, respectively). The expression levels of Livin and PlGF were independent prognostic factors for patients with osteosarcoma. The results of the present study demonstrated that Livin and PlGF may participate in the pathogenesis of osteosarcoma. Therefore, pharmacological inhibition of Livin or PlGF may provide a novel strategy for osteosarcoma treatment.

[Application progress of seed cells in tissue engineered nerve].

OBJECTIVE: To summarize the applications of Schwann cells (SCs), stem cells, and genetically modified cells (GMCs) in repair of peripheral nerve defects. METHODS: The literature of original experimental study and clinical research related with SCs, stem cells, and GMCs was reviewed and analyzed. RESULTS: SCs play a key role in repair of peripheral nerve defects; the stem cells can be induced to differentiate into SCs, which can be implanted into nerve conduits to promote the repair of peripheral nerve defect; genetically modified technology can enhance the function of SCs and different stem cells, which has been regarded as a new option for tissue engineered nerve. CONCLUSION: Although great progress has been made in tissue engineered nerve recently, mostly limited to the experimental stage. The research of seed cells in application of tissue engineered nerve need be studied deeply.

Study of sensory and motor fascicles in brachial plexus and establishment of a digital three-dimensional graphic model.

To investigate a 3-dimensional (3D) model of human brachial plexus including its topography of sensory and motor fascicles with the assistance of the computer technology, 2 brachial plexus were serially horizontally sliced. Each slice was stained by Karnovsky-Roots acetylcholinesterase histochemical method. The stained sections were scanned, and the image was put into the computer serially. At last, the 3D diagram of brachial plexus was made. The internal structure of the brachial plexus was found to be very complicated. The fascicles bifurcated and recombined with one another with no fixed rules. All fascicles were mixed sensory and motor fibers. Acetylcholinesterase histochemical staining from a serial tissue section is a useful technique to distinguish sensory fibers from motor ones. The 3D visualization of the brachial plexus may help to develop a computerized database of the fascicle topography to provide an anatomical reference in fascicular repair of brachial plexus.

Synthetic osteogenic growth peptide promotes differentiation of human bone marrow mesenchymal stem cells to osteoblasts via RhoA/ROCK pathway.

The osteogenic growth peptide (OGP) is a naturally occurring tetradecapeptide that has attracted considerable clinical interest as a bone anabolic agent and hematopoietic stimulator. In vitro studies have demonstrated that OGP directly regulates the bone marrow mesenchymal stem cells' (BMSCs) differentiation into osteoblasts. However, the exact mechanism of this process remains unknown. In the present study, we investigated the role of RhoA/ROCK signaling in differentiation along this lineage using human BMSCs. OGP treatment increased the mRNA level of bone morphogenetic protein-2 and alkaline phosphatase activity after osteogenic induction. Analysis of BMSCs induced in the presence of OGP revealed an increase in RhoA activity, and phosphorylation of FAK and cofilin. The ROCK-specific inhibitors, Y27632, blocked the OGP-induced regulation of BMSC differentiation. Taken together, these data suggest that OGP not only acts on BMSCs to stimulate osteogenic differentiation, but also in a dose-dependent manner, and this effect is mediated via the activation of RhoA/ROCK pathway.

Dextran-g-PEI nanoparticles as a carrier for co-delivery of adriamycin and plasmid into osteosarcoma cells.

Combination of chemotherapy and gene therapy of cancer has synergistic effects on overcoming drug resistance. Macromolecular materials such as dextran and PEI have been a potential module for chemotherapeutics and gene delivery. Herein, we hypothesize the combinational strategy of chemotherapy and gene therapy in a single dextran-PEI nanoplatform. The physicochemical properties, cytotoxicity, transfection efficiency were investigated in vitro. Ultra-violet spectrum and (1)H NMR revealed adriamycin and PEI were grafted to dextran chain. Agarose gel electrophoresis demonstrated that the migration of plasmid was completely retarded when the N/P ratio of complex was 4. The sizes of DEX-ADM-PEI/DNA nanoparticles decreased and the zeta potentials enhanced with the increasing N/P ratio. Transmission electron microscope indicated a round morphology of the nanoparticles. DEX-ADM-PEI conjugation has higher cytotoxicity, compared to free adriamycin, in MG-63 and Saos-2 osteosarcoma cells but DEX-PEI maintained over 65% cell viability at the concentration of 8 mg/mL. The transfection efficiency of DEX-ADM-PEI/pEGFP-N1 at N/P ratio of 4:1 both in MG-63 and Saos-2 cell were slightly low than that of PEI 25k. But our nanoplatform efficiently delivered both plasmid pEGFP-N1 and adriamycin into osteosarcoma cells. This study demonstrated that DEX-ADM-PEI efficiently and selectively delivered both plasmid pEGFP-N1 and adriamycin to osteosarcoma cells with low cytotoxicity.

Osteogenic growth peptide enhances the proliferation of bone marrow mesenchymal stem cells from osteoprotegerin-deficient mice by CDK2/cyclin A.

To promote bone formation is one of the fundamental strategies in osteoporosis treatment and fractures repair. As one of the stimulators on bone formation, osteogenic growth peptide (OGP) increases both proliferation and differentiation of the osteoblasts in vitro and in vivo, in which osteoprotegerin (OPG) has been suggested being involved. In this study, we evaluated the effects of OGP on bone marrow mesenchymal stem cells (MSCs) from OPG-deficient mice in vitro by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, alkaline phosphatase (ALP) activity assay, real-time polymerase chain reaction, and western blot analysis. Results showed that OGP stimulated MSC proliferation and increased the expression of CDK2 and cyclin A in MSCs both at mRNA and protein levels. However, no differentiative effect of OGP was shown as ALP activity and the expression levels of Runx2 and Osterix were not increased significantly by OGP. Our study suggested that OGP may increase the bone formation in OPG-deficient mice by stimulating MSC proliferation rather than differentiation, and probably by triggering CDK2/cyclin A pathway.

[Allografted olfactory mucosa gliacytes repair Wistar rats' sciatic nerve long defect].

OBJECTIVE: To investigate whether or not allografted olfactory mucosa gliacytes could repair peripheral nerve injure. METHODS: Olfactory mucosa gliacytes had been cultured in vitro for 2 weeks, then purified and condensed for later transplantation.Sixty adult female Wistar rats were randomized into 2 groups of 30 rats each, A (control) and B (test). Rats' left sciatic nerves were excised 25 mm long axons and retained epineurium lumen anastomosed to proximal ends. Culture mediums, and olfactory mucosa gliacytes were transplanted into epineurium lumen of A and B groups respectively. At 3 months postoperatively, the regenerations of injured sciatic nerves were evaluated by methods of macroscopy, photomicroscopy, transmission electron microscopy, retro-marked fluorescence red, the condensation of glial fibre acid protein (GFAP) and nerve growth factors (NF) assayed by immunofluorescence, and the concentration of myelin basic protein (MBP) and neurofilament protein (NF) assayed by enzyme linked immunosorbent assay. RESULTS: The regenerations of injured sciatic nerves were superior in B group to in A group; the transportation distance of retro-marked fluorescence red were longer in B group than in A group (P < 0.01). The condensations of GFAP and NGF were more dense in B group than in A group. The concentrations of MBP and NF were more high in B group than in A group (P < 0.01). The function scores of injured limbs were superior in B group to in A group (P < 0.01). The quantifications of nerve fibers and myelin fibers of injured sciatic nerve were larger in B group than in A group (P < 0.01). CONCLUSION: Allografted olfactory mucosa gliacytes could repair injured nerve defect.

Repair of partial nerve injury by bypass nerve grafting with end-to-side neurorrhaphy.

The purpose of this study was to investigate the efficacy of bypass nerve grafting with end-to-side neurorrhaphy in repair of the partial nerve injury in a rabbit model. Thirty-six adult male New Zealand rabbits were divided into three groups. A partial nerve injury was created by removal of a segment of the lateral fascicle of the left peroneal nerve. In group one, the injured nerve was repaired with nerve graft bypassing the injury site in an end-to-side fashion 4 weeks after injury. In group two, the injured nerve was repaired with end-to-end interpositional nerve grafting 6 weeks after injury. The injured nerve without repair was used as the control. Sixteen weeks after nerve repair, in groups one and two, and 20 weeks after the initial nerve injury in the control group, the nerves were dissected for electrophysiological examination and biopsied for histology and molecular markers expression. The nerve repair with interpositional nerve grafting achieved maximal functional recovery. However, motor nerve conduction velocity and compound motor action potential in nerve repair with bypass nerve grafting were significantly higher than that in the nerve injury without repair. Histologically, the regenerated myelinated axons and unmyelinated axons were present in the distal peroneal nerves in the bypass nerve grafts. The axon counts in nerve repair with the bypass nerve grafting were also significantly higher than that in the nerve injury without repair. The comparisons of the ciliary neurotrophic factor and the calcitonin gene-related peptide gene expressions between nerves with and without repair were significantly different. End-to-side bypass nerve grafting can significantly improve functional recovery in the nerve with partial injury and may be a useful repair strategy in neuromas-in-continuity.

Three-dimensional reconstruction and visualization of the median nerve from serial tissue sections.

The purpose of this study was to definitively implement the three-dimensional visualization of sensory and motor fascicles in the human median nerve by means of acetylcholinesterase (AChe) histochemical staining and under the assistance of the computer technology. One fresh human median nerve was harvested from a male adult cadaver. The median nerve was fixed at a special holder. Then, the whole holder was embedded and rapidly frozen in the liquid nitrogen. The processed median nerve was then cut coronally every 100 microm at a 20 microm thickness along its long axis in a sliding freezing microtome. The total number of sections was 4,650 slices. All sections were stained with the AChe histochemical method. The stained sections were scanned and saved as Joint Photographic Experts Group files. These images with positively and negatively stained sections were acquired to an Intel dual Pentium computer. The Adobe Photoshop CS2 software was used to compare the reference points of images before and after staining. The two-dimensional intraneural microstructure database of median nerve was then acquired. A software of 3D nerve visualization system was developed. With the 3D nerve visualization system, the 3D visualization result of intraneural microstructure of median nerve was created. The findings may provide more accurate and detailed anatomic information for nerve repairs, specifically for the fascicular nerve repairs. The 3D nerve visualization technique may have potential for future studies of topography of peripheral nerve. (c) 2009 Wiley-Liss, Inc. Microsurgery, 2009.

[Bone inductive effects of rhBMP-2 loaded porous CPC implants on spine fusion in rabbits].

OBJECTIVE: To investigate the effect of rhBMP-2 combined with porous CPC on spine fusion in rabbits. METHODS: rhBMP-2 (1 mg) was loaded with 1 g CPC and 6.0 cm x 2.0 cm x 0.5 cm absorbable gelatin sponge (AGS), respectively, and thereafter frozen to prepare the biomaterial of rhBMP-2/CPC and rhBMP-2/AGS. Forty-five 24-week-old New Zealand rabbits (weight 2.5-3.5 kg) were randomly divided into 3 groups: group A (n=17), group B (n=11) and group C (n=17). With the exposure and removal of L5,6 transverse process's posterior bone cortex in all the rabbits, the corresponding cancellous bones were exposed and the posterior bilateral intertransverse bone grafting of L5,6 were performed on the three groups, then the rhBMP-2/CPC, rhBMP-2/AGS and CPC was implanted into the rabbits of group A, B and C, respectively. Gross observation, histology assay and image examination were conducted 4, 8 and 24 weeks after operation. RESULTS: Decalcified hard tissue section demonstrated obvious callus connections in group A, small pieces of callus in group B, and fibrous connection and few cartilage in group C at 4 and 8 weeks after operation. By Kacena measurement standard, the score of group A, B and C at 4 weeks after operation was (7.30 +/- 0.76), (3.68 +/- 1.60) and (1.75 +/- 0.54) points, respectively, and their score at 8 weeks after operation were (8.32 +/- 1.11), (3.75 +/- 1.23) and (1.47 +/- 0.23) points, respectively, indicating there were significant differences between group A and group B as well as between group A and group C at different time points (P < 0.05). Undecalcified hard tissue section demonstrated that there was cancellous bone-like tissue regeneration in group A, and fiber connection around the implants and little ossification in group C at 4 and 8 weeks after operation. By three dimensions reconstructed CT, group A, B and C scored (2.50 +/- 0.57), (1.00 +/- 0.00) and (1.00 +/- 0.00) points respectively, indicating there was a significant difference between group C and groups A and B as well as between group A and group B (P < 0.05). CONCLUSION: As a carrier of rhBMP-2, the CPC is capable of promoting spine bone fusion in rabbits and is a new type of artificial bone repair material.

[Comparison of competence of olfactory globular nerve layer gliocytes, olfactory epithelial gliacytes and SC in repairing nerve defect].

OBJECTIVE: To compare their competence of olfactory epithelial gliocytes, olfactory globular nerve layer (OGNL) gliocytes and SC in repair nerve defect of sciatic nerve, and select the best gliocytes for repair of peripheral nerve defect. METHODS: Olfactory epithelial gliocytes, OGNL gliocytes and SC were extracted from 20 female Wistar rats aged 2-3 months and cultured in vitro for 2 weeks, then purified and condensed for transplantation. Eighty adult female Wistar rats were randomized into groups A, B, C and D (n = 20). The left sciatic nerves were excised 25 mm axons and retained epineurium lumen anastomosed to proximal ends. The culture mediums, SC, OGNL gliocytes, and olfactory epithelial gliocytes were transplanted into the epineurium lumen of groups A, B, C and D, respectively. Three months postoperatively, the injured sciatic nerve regeneration was evaluated by methods of macroscopic observation, photomicroscope, transmission electron microscope, retro-marked fluorescence transportation distance, the glial fibrillary acidic protein (GFAP) and nerve growth factor (NGF) were assayed by immunofluorescence, and the myelin basic protein (MBP) and neurofilament (NF) protein were assayed by ELISA. RESULTS: The scores of ankle joint were (3.325 +/- 0.963), (4.200 +/- 1.005), (5.143 +/- 0.635) and (5.950 +/- 0.154) in groups A, B, C and D, respectively; showing statistically significant difference between groups (P < 0.05). The observations of gross, sections under microscope and transmission electron microscope showed the regeneration of defect nerve was best in group D, followed by group C, and group B was superior to group A. The transportation distance of retro-marked fluorescence was longest in group D, followed by group C, and group B was superior to group A. The concentrations of GFAP and NGF were largest in group D, followed by group C, and group B was superior to group A. The MBP concentrations were (9.817 +/- 3.267), (12.347 +/- 3.091), (14.937 +/- 2.075) and (22.757 +/- 0.871) ng/mL in groups A, B, C and D, respectively; showing statistically significant difference between other groups (P < 0.05) except between group A and group B (P > 0.05). And the NF concentrations were (13.869 +/- 5.677), (18.498 +/- 3.889), (23.443 +/- 2.260) and (27.610 +/- 1.125) ng/mL in groups A, B, C and D, respectively; showing statistically significant difference between groups (P < 0.05). CONCLUSION: Olfactory epithelial gliocytes, OGNL gliocytes and SC transplantation could repair injured nerve. The competence of olfactory epitheliums is superior to the OGNL gliocytes and SC, and the OGNL gliocytes is better than SC.

[3D visualization research on microstructure of human ulnar nerve].

OBJECTIVE: To explore the application of 3D nerve visualization system in processing 2D image information of human ulnar nerve acquired by series freezing tissue section, staining and scanning. And to draw the 3D anatomical atlas of human ulnar nerve through 3D Nerve visualization software system. METHODS: One left ulnar nerve (from medial fasciculus of brachial plexus to transverse carpal ligament, about 50 cm) was taken from a fresh donated cadaver. After marked with human hair and embedded in OCT, series freezing tissue sections were made and stained with acetylcholinesterase histochemically. Series 2D image information was obtained through high resolution scanner. Then the microstructure of ulnar nerve was reconstructed with 3D Nerve visualization software system. RESULTS: Different cross sections of ulnar nerve have different numbers, positions and characters of the internal nerve fibers. The microstructure of ulnar nerve could be observed in magnifying visual field at any cross section after reconstructed in 3D Nerve visualization soft ware system, which made it possible to track stereo course of fascicles. CONCLUSION: Reconstructed 3D Nerve visualization software system shows the whole microstructure of ulnar nerve and the 3D stereo-structure of its internal fascicles, thus provides exact topography atlas for medical teaching and facilitates precise repair of ulnar nerve injury to improve therapeutic effect.

Improved long-term recording of nerve signal by modified intrafascicular electrodes in rabbits.

Methods for long-term recording of peripheral nerve activity via intrafascicular electrodes have not been optimized. We compared the long-term functionality of custom-made 95%Pt/5%Ir intrafascicular electrodes containing a proximal spring-like structure to that of conventional straight electrodes. The modified electrode was implanted into the sciatic nerve fascicle of a random hind limb in 14 rabbits for 9 months. A conventional electrode was implanted in the opposite hind limb as a control. Orthodromic and antidromic nerve potentials were sampled and analyzed monthly. Latency, amplitude, and nerve conduction velocity of electrical signals were generally similar within the modified group and straight control group at different time intervals (P > 0.05). However, at the conclusion of the study period, the modified electrode group had a greater number of functioning electrodes (P < 0.05) and a greater total functioning electrode time (P = 0.006). Intrafascicular electrodes with a spring-like structure demonstrated superior potential for long-term electrophysiological monitoring over straight electrodes.

Recording and stimulating properties of chronically implanted longitudinal intrafascicular electrodes in peripheral fascicles in an animal model.

The purpose of this experiment was to study the recording and stimulating properties, and biocompatibility of longitudinally implanted intrafascicular electrodes (LIFEs) in a rabbit sciatic nerve model when they were chronically implanted into peripheral fascicles. LIFEs were implanted chronically into sciatic nerve fascicles of rabbits as recording and stimulating electrodes. Motor-evoked potentials (MEPs) and cortical somatosensory-evoked potentials (CSEPs) were recorded by using a transcranial stimulation system (TCS) over 6-month period to observe the change of the signals recorded. At the end of the experiment, the fascicles at the electrodes implanted site were anatomized for histological examination under light microscope and transmission electron microscope. Results showed onset latency (OL) of MEPs and CSEPs had no obvious change during the first month. However, OL significantly increased during the second month, and then became stable 3 months after implantation. The interpeak amplitudes (IPAs) of MEPs had no distinct change during the first month, but significantly decreased over the next period, and then became stable 3 months after implantation. The IPAs of CSEPs, however, decreased slowly over the 6-month period of the study. At the end of the experiment, histological examination indicated that a typical foreign body reaction developed, and electrodes caused mild damage to the fascicles, though inflammatory cells and neuroma were not seen around the electrodes. In conclusion, LIFEs have excellent recording and stimulating characters in addition to biocompatibility with peripheral fascicles. They can be implanted chronically into fascicles and record signals.

Residual motor signal in long-term human severed peripheral nerves and feasibility of neural signal-controlled artificial limb.

PURPOSE: The residual motor pathways after amputation have not been fully elucidated. We sampled potentials from peripheral nerve stumps with intrafascicular electrodes to study residual motor transmission and explore the feasibility of nerve signal-controlled artificial limbs. METHODS: Six intrafascicular electrodes were inserted into the ulnar, radial, and median nerves in the stump of an amputee. An electrode was placed outside the fascicle as a reference. Potentials from 4 of the 6 electrodes per trial were monitored using a 4-channel electromyogram machine, and 32 groups of electrophysiologic tests were conducted under volitional control. Actions included finger extension and flexion, forearm pronation and supination, and wrist extension and flexion. Each action was carried out with light, intermediate, and full efforts. Then, 2 of 6 electrodes randomly chosen per trial were interfaced to a nerve signal-controlled artificial limb. Finger extension and flexion of the prosthesis were tested under volitional control. RESULTS: The volitional motor nerve potentials uniquely associated with the missing limb were recorded successfully with intrafascicular electrodes. The signal amplitude from the radial nerve was 5.5 microV +/- 0.8 (mean +/- SD), which was greater than the amplitudes from the ulnar (2.5 microV +/- 0.4) and median (2.2 microV +/- 0.3) nerves. Under volitional control of the subject, finger extension of the artificial limb was triggered by the radial nerve signal, but the remaining actions were unsuccessful. CONCLUSIONS: The long-term amputee was able to generate motor neuron activity related to phantom limb movement. Intrafascicular electrodes can be used to monitor residual motor nerve activity in the stump, and the amplitude may predict successful control of artificial limbs.

Biomechanical study of a hat type cervical intervertebral fusion cage.

The purpose of this study was to evaluate the biomechanical effect of a hat type cervical intervertebral fusion cage (HCIFC). In this in vitro biomechanical study, 48 goat cervical spines (C2-5) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method using a nonconstrained testing apparatus, and three-dimensional displacement was measured. Autologous iliac bone and cervical spine intervertebral fusion cage were implanted according to manufacturers' information after complete discectomy (C3-4). Eight spines in each of the following groups were tested: intact, autologous iliac bone graft, Harms cage, SynCage C, carbon cage, and HCIFC. The mean apparent stiffness values were calculated from the corresponding load-displacement curves. Additionally, cage volume and volume-related stiffness were determined. The stiffness of the SynCage C was statistically greatest in all directions. After implantation of the HCIFC, flexion stiffness increased compared with that of the intact motion segment. There was no significant difference in stiffness between the HCIFC and carbon cage. The stiffness of the HCIFC was statistically higher than that of the Harms cage in axial rotation and significantly lower in flexion, extension, and lateral bending. Volume-related stiffness of all cages was higher than that of iliac bone graft. The Harms cage was highest in volume-related stiffness in all directions. The HCIFC can provide enough primary stability for cervical intervertebral fusion.

Changes with age and the effect of recombinant human BMP-2 on proteoglycan and collagen gene expression in rabbit anulus fibrosus cells.

In order to compare the difference between young and old intervertebral disc cells and their responsiveness to recombinant human bone morphogenetic protein-2 (rhBMP-2), disc cells were isolated from the anulus fibrosus (AF) and transition zones of lumbar discs from eight old and eight young New Zealand white rabbits. Compared with the cells from the young rabbits, cells from old rabbits respond less to rhBMP-2 treatment with respect to sulfated-glycosaminoglycan (sGAG) synthesis and aggrecan gene expression. But in collagen I and collagen II gene expressions, there are no significant differences between the old and the young. When comparing sGAG content, aggrecan, and collagen II gene expression of the old AF cells after rhBMP-2 treatment with that of the young AF cells without rhBMP-2 treatment, the old AF cells with rhBMP-2 treatment have a greater capacity to synthesize sGAG bound in the cells and to release sGAG in the media, as well as to express aggrecan and collagen II gene. It can be concluded that old AF cells after rhBMP-2 treatment have a greater capacity to synthesize sGAG and express aggrecan and collagen II as compared to young AF cells without rhBMP-2 treatment. Thus rhBMP-2 can reverse the decline in the anabolic capacity of the disc cells with ageing. So it seems that rhBMP-2 has potential for use as an agent to retard a key component of disc degeneration and loss of disc matrix.

[In vivo experimental study of hat type cervical intervertebral fusion cage].

OBJECTIVE: To compare the characteristics of interbody fusion achieved using hat type cervical intervertebral fusion cage (HCIFC) with those of an autologous tricortical iliac crest graft, Harms cage and Carbon cage in a goat cervical spine model. METHODS: Thirty-two goats underwent C(3, 4) discectomy and fusion in which the following were used: Group 1, autologous tricortical iliac crest bone graft (8 goats); Group 2, Harms cage filled with autologous iliac crest graft (8 goats); Group 3, Carbon cage filled with autologous iliac bone (8 goats); Group 4, HCIFC filled with autologous iliac graft (8 goats). Radiography was performed pre- and postoperatively and after 1, 2, 4, 8, and 12 weeks. At the same time points, disc space height, intervertebral angle, and lordosis angle were measured. After 12 weeks, the goats were killed and fusion sites were harvested. Biomechanical testing was performed in flexion, extension, axial rotation, and lateral bending to determine the stiffness and range of motion. All cervical fusion specimens underwent histomorphological analysis. RESULTS: One week after operation, the DSH, IVA and LA of HCIFC and Carbon cage were statistically greater than those of autologous iliac bone graft and Harms cage. Significantly higher values for disc space height, intervertebral angle and lordosis angle were shown in cage-treated goats than in those that received bone graft over a 12-week period. The stiffness of Harms cage in axial rotation and later bending were statistically greater than that of other groups. Radiographic and histomorphologic evaluation showed better fusion results in cage groups than in autologous bone group. CONCLUSIONS: HCIFC can provide a good intervertebral distractability and enough biomechanical stability for cervical fusion.

[Experimental study on magnesium phosphate cement in fracture treatment].

OBJECTIVE: To investigate the effect of magnesium phosphate cement (MPC) to fix fractures. METHODS: In vitro: fifty-four pairs of fresh pig femoral heads were made 1 cm2 fracture and divided into 6 groups (n=9 pairs ). MPC was used to agglutinate fracture of femoral heads at 100% humidity and at 25 degrees C, 37 degrees C respectively. At 30 minutes, 2 and 24 hours after agglutination, the biomechanical strength was measured. In vivo: the tibia plateau fracture models on both sides of 24 rabbits were made, one side was fixed with "L" shaped plate, and the other side was fixed with MPC. Then the effect of treatment was investigated by macrography, micrography, radiography and the In vitro: the adhesive ability of changes of serum electrolyte levels at 3 days, 3, 6 and 9 weeks after operation. RESULTS: MPC was strong. At 24 hours after MPC agglutination, the average tensile strength was 117.16 +/- 23.29 N/cm2. In vivo: after 6 weeks of fixation, the X-ray results showed that all rabbits' tibia plateau fractures were healed without displacement, and MPC was absorbed gradually. The changes of serum electrolyte levels were very minimal. The macrography observation showed that reduction of fracture were good at 3 days after operation, partial MPC remained in fracture end at 3 weeks, fracture line disappeared at 6 weeks and good remodeling was achieved at 9 weeks after operation in the experimental group. The micrography observation showed that the interface between bone and MPC was distinct at 3 days, MPC was degraded gradually and trabeculae began to grow into MPC at 3 weeks, and almost all MPC was degraded at 6 and 9 weeks of operation. CONCLUSION: MPC is a promising biomaterial, and might potentially be used for fracture treatment.