Enhancement of the synthesis of n-3 PUFAs in fat-1 transgenic mice inhibits mTORC1 signalling and delays surgically induced osteoarthritis in comparison with wild-type mice.

BACKGROUND: An exogenous supplement of n-3 polyunsaturated fatty acids (PUFAs) has been reported to prevent osteoarthritis (OA) through undefined mechanisms. OBJECTIVE: This study investigated the effect of alterations in the composition of endogenous PUFAs on OA, and associations of PUFAs with mammalian target of rapamycin complex 1 (mTORC1) signalling, a critical autophagy pathway in fat-1 transgenic (TG) mice. METHODS: fat-1 TG and wild-type mice were used to create an OA model by resecting the medial meniscus. The composition of the endogenous PUFAs in mouse tissues was analysed by gas chromatography, and the incidence of OA was evaluated by micro-computed tomography (micro-CT), scanning electron microscopy and histological methods. Additionally, primary chondrocytes were isolated and cultured. The effect of exogenous and endogenous PUFAs on mTORC1 activity and autophagy in chondrocytes was assessed. RESULTS: The composition of endogenous PUFAs of TG mice was optimised both by increased n-3 PUFAs and decreased n-6 PUFAs, which significantly alleviated the articular cartilage destruction and osteophytosis in the OA model (p<0.01), decreased protein expression of matrix metalloproteinase-13 (MMP-13) and ADAMTS-5 (a disintegrin and metalloproteinase with thrombospondin motifs) in the articular cartilage (p<0.01) and reduced chondrocyte number and loss of cartilage extracellular matrix. Both exogenous and endogenous n-3 PUFAs downregulated mTORC1 activity and promoted autophagy in articular chondrocytes. Conversely, mTORC1 pathway activation suppressed autophagy in articular chondrocytes. CONCLUSIONS: Enhancement of the synthesis of endogenous n-3 PUFAs from n-6 PUFAs can delay the incidence of OA, probably through inhibition of mTORC1, promotion of autophagy and cell survival in cartilage chondrocytes. Future investigation into the role of the endogenous n-6/n-3 PUFAs composition in OA prevention and treatment is warranted.

Endogenous n-3 polyunsaturated fatty acids (PUFAs) mitigate ovariectomy-induced bone loss by attenuating bone marrow adipogenesis in FAT1 transgenic mice.

AIM: To investigate the effect of endogenous n-3 polyunsaturated fatty acids (PUFAs) on bone marrow adipogenesis under osteoporosis conditions. METHODS: A mouse osteoporosis model overexpressing the FAT1 gene from Caenorhabditis elegans and converting n-6 PUFAs to n-3 PUFAs endogenously was used. RESULTS: The mice presented significantly lower bone marrow adiposity (adipocyte volume/tissue volume, mean adipocyte number) but increased the bone parameters (bone mineral density, bone mineral content, bone volume/total volume) in the distal femoral metaphysis. CONCLUSION: Endogenous n-3 PUFAs protect bone marrow adipogenesis, which provides a novel drug target.

Could heterotopic ossification be prevented by varying dietary n-3/n-6 polyunsaturated fatty acid ratio: a novel perspective to its treatment?

Heterotopic ossification (HO) is a common complication following with musculoskeletal trauma and surgical procedures. It usually decreases joint mobility and eventually causes loss of joint function. Despite nonsteroidal anti-inflammatory drugs (NSAIDs), the inhibitor of cyclooxygenase(COX), have been proven to prevent HO effectively via prostaglandin E2 synthesis regulation and modulation of tissue responsiveness to pro-inflammatory signaling, HO prevention is still a matter of debate for clinicians to avoid the side effect of NSAIDs. Interestingly, it is suggested that PGE2 production and pro-inflammatory microenvironment in body could be modified by varying the ratio of the precursor fatty acids in the diet. On account of the effect of dietary (n-6)/(n-3) PUFAs ratio on both COX metabolism and pro-inflammatory cytokines mediated biological responsiveness, we hypothesized lowering dietary (n-6)/(n-3) PUFAs ratio may not only directly reduce the substrate of COX-2 and COX-2 activity, but also partially ameliorate tissue inflammatory responsiveness to cytokines correlated with HO development,exerting an inhibitory effect on PGE2 synthesis to prevent HO formation. The negative role of lowering dietary (n-6)/(n-3) PUFAs ratio on angiogenesis, cytokines-induced apoptosis, inflammatory responsiveness and osteogenesis could also contribute to its action on HO development. If our hypothesis is proved to be corrected, it could be an innovative method to treat HO.

[In vivo experimental study of lumbar nucleus replacement with pectin/polyvinyl alcohol composite hydrogel].

OBJECTIVE: To evaluate the anti degenerative effect of pectin/polyvinyl alcohol composite (CoPP) hydrogel as artificial nucleus material in an animal model. METHODS: Thirty-six New Zealand white rabbits were used to build animal models, the L4₋5 intervertebral discs were pierced with a Gauge#16 needle and polyvinyl alcohol (PVA) or CoPP implants were inserted into the holes. For comparative purposes, L3₋4 discs underwent sham treatment or control treatment in which the disc was pierced but no implant was inserted. All the discs were divided into four groups as follows: sham disc group, pierced disc group, PVA disc group and CoPP disc group. The discs were analyzed radiologically and histologically for degenerative changes at 1, 3 or 6 months after surgery. RESULTS: None of the animals died from operative complications, such as paraplegia or infection before being killed. Macroscopically, none of the implants showed any signs of displacement at the time of harvest. The radiological analysis revealed that significantly less disc height loss was found with the PVA and CoPP replacement treatment than with the pierced treatment (P < 0.05). Changes in disc height after the replacement treatment were not significantly different from that after the sham treatment (P > 0.05). Histological degeneration of the replaced discs was delayed in comparison with that of the pierced discs (P < 0.05), but progressed with time, and PVA replacement showed faster disc degeneration than CoPP replacement. CONCLUSIONS: Degeneration of the anulus fibrosus after the CoPP prosthetic nucleus replacement treatment is delayed by preserving disc height and occupying the space of the nucleus pulposus, and it has great potential clinical application value.

Evaluation of biocompatibility of a pectin/polyvinyl alcohol composite hydrogel as a new nucleus material.

OBJECTIVE: To evaluate the biocompatibility of a new kind of prosthetic nucleus: a pectin/polyvinyl alcohol composite (CoPP) hydrogel. METHODS: According to Chinese national standard GB/-T16886 documents, the toxicity of the CoPP prosthetic nucleus material was examined by cytotoxicity, sensitization, Ames, mice marrow micronucleus, chromosome aberration test of mammalian cell and implantation tests. RESULTS: Cell growth was similar in the CoPP culture and control groups. No significant difference was found between the CoPP culture and control groups at each time point (P > 0.05). The cell proliferation rate was greater than 100%. In accordance with the relationship between cytotoxicity to proliferation rate, it was confirmed that the cytotoxicity of CoPP was 0 grade. Mice had no allergic reaction when injected with an extract of CoPP. A reverse mutation test with Salmonella typhimurium showed that no significant effect on the number of histidine revertants of TA97, TA98, TA100 and TA102 strains after CoPP was added. The micronucleus rate in bone marrow cells was less than 5%; there was no significant difference compared with the negative control group (P > 0.05). The rate of chromosome aberration was less than 5%; no significant difference was found between the CoPP culture and the control groups. All experimental animal wounds achieved primary healing without exudation, infection or sinus formation. On macroscopic observation, no abscess or hematoma formed at the implantation site. CONCLUSION: The CoPP prosthetic nucleus has good biocompatibility and can potentially be used as an implant material.

[Evaluation of the biocompatibility of pectin/poly vinyl alcohol composite hydrogel as a prosthetic nucleus pulposus material].

OBJECTIVE: To evaluate the biocompatibility of pectin/poly vinyl alcohol composite (CoPP) hydrogel for use as a prosthetic nucleus pulposus material. METHODS: The in vitro cytotoxicity of CoPP hydrogel was tested in NCTC L929 cells, which were divided into normal control group, negative control group [treated with poly (vinyl alcohol) hydrogel, PVA], experimental group (treated with CoPP) and positive control group (0.64% phenol). The optical density of the cells on days 2, 4, and 7 of the corresponding treatments was determined and the relative growth rate calculated. For in vivo biocompatibility evaluation, dehydrated CoPP and PVA hydrogel were respectively implanted into the left and right gluteus of SD rats, and the wound healing and general status were observed. The muscular tissues containing the implants were taken 1, 4, and 12 weeks after the implantation for gross observation and microscopic observation of the inflammatory cell infiltration (ICI) and formation of the fibrous capsulation around the implants. RESULTS: The L929 cells incubated with PVA and CoPP group both grew well, with relative growth rate over 80% and 75%, respectively. The cytotoxicity of PVA and CoPP was both lower than grade 1. In contrast, the relative growth rate in the positive control group was below 24%, with cytotoxicity over grade 4. In the SD rats, ICI of grade IV occurred in the muscular tissues around the PVA and CoPP implants at 1 week without formation of complete capsule, and at 4 weeks, ICI was lowered to grade 1 with grade 4 capsular reaction. Till week 12, the ICI and capsular reaction were both first grade. CONCLUSION: CoPP hydrogel has in vitro grade 0 or 1 cytotoxicity and causes only mild inflammation after implantation in rats, suggesting good biocompatibility of the material.

[Evaluation of perioperative blood loss following total knee arthroplasty].

OBJECTIVE: To evaluate perioperative occult blood loss following total knee arthroplasty (TKA). METHODS: A retrospective analysis of 40 patients undergoing TKA was conducted to calculate the mean blood loss and occult blood loss according to Gross formula. RESULTS: The mean total blood loss was 1538 ml in these cases with occult blood loss of 791 ml. In patients with autologous blood transfusion, the mean total blood loss was 1650 ml with occult blood loss of 786 ml. In patients without autologous blood transfusion, the mean total blood loss was 1370 ml with occult loss of 798 ml. CONCLUSION: TKA often results in large volume of occult blood loss in the perioperative period which can not be fully compensated by autologous blood transfusion, and additional blood supply is needed for maintenance of the circulating volume.

[Effects of Yunnan Baiyao on peri-operative bleeding of patients undergoing cervical open-door laminoplasty: a multi-center randomized double-blind placebo-control trial].

OBJECTIVE: To investigate the effects of Yunnan Baiyao on peri-operative bleeding of the patients undergoing cervical open-door laminoplasty. METHODS: 197 patients undergoing cervical open-door laminoplasty were randomly divided into 2 groups Yunnan Baiyao group (receiving Yunnan Baiyao 500 mg three times daily for 5 days) and placebo group. The amounts of intra-operative and post-operative bleeding were compared, and the side effect of Yunnan Baiyao was also analyzed. RESULTS: Statistical analysis showed that the amount of intra-operative bleeding of the Yunnan Baiyao was 350 ml +/- 190 ml, significantly lower than that of the placebo group (443 ml +/- 266 ml, P < 0.05). There were no statistical differences in the amount of postoperative bleeding and side effect rate between the two groups. CONCLUSION: Yunnan Baiyao is effective and safe in reducing the amount of intra-operative bleeding of cervical open-door laminoplasty.