Vascular Canals in Permanent Hyaline Cartilage: Development, Corrosion of Nonmineralized Cartilage Matrix, and Removal of Matrix Degradation Products

"Cross-talk" between gut microbiome dysbiosis and osteoarthritis progression: a systematic review

Objectives

The aim of this systematic review was to summarize the available literature on gut microbiome (GMB) and osteoarthritis (OA), analyze the correlation between GMB and OA, and explore potential underlying mechanisms.

Methods

A systematic search of the PubMed, Embase, Cochrane, and Web of Science with the keywords "Gut Microbiome" and "Osteoarthritis" was conducted to identify the human and animal studies exploring the association between GMB and OA. The retrieval time range was from the database inception to July 31, 2022. Studies reported the other arthritic diseases without OA, reviews, and studies focused on the microbiome in other parts of the body with OA, such as oral or skin, were excluded. The included studies were mainly reviewed for GMB composition, OA severity, inflammatory factors, and intestinal permeability.

Results

There were 31 studies published met the inclusion criteria and were analyzed, including 10 human studies and 21 animal studies. Human and animal studies have reached a consistent conclusion that GMB dysbiosis could aggravate OA. In addition, several studies have found that alterations of GMB composition can increase intestinal permeability and serum levels of inflammatory factors, while regulating GMB can alleviate the changes. Owing to the susceptibility of GMB to internal and external environments, genetics, and geography, the included studies were not consistent in GMB composition analysis.

Conclusion

There is a lack of high-quality studies evaluating the effects of GMB on OA. Available evidence indicated that GMB dysbiosis aggravated OA through activating the immune response and subsequent induction of inflammation. Future studies should focus on more prospective, cohort studies combined with multi-omics to further clarify the correlation.

Growth factor profile in calcified cartilage from the metaphysis of a calf costochondral junction, the site of initial bone formation

Endochondral bone formation is orchestrated by growth factors produced by chondrocytes and deposited in the cartilage matrix. Whilst some of these factors have been identified, the complete list and their relationship remains unknown. In the present study, the growth factors were isolated from non-calcified and calcified cartilage of costochondral junctions. Cartilage dissected from the ribs of 6-20-week-old calves was purchased from a local butcher within 24 h of the death of the animal. The isolation involved hyaluronidase digestion, guanidinium hydrochloride (GuHCl) extraction, HCl decalcification and GuHCl extraction of the decalcified matrix. Growth factors were purified by heparin chromatography and their quantities were estimated using ELISA. Decalcified cartilage was also used for protein sequence analysis (data are available via ProteomeXchange; ID, PXD021781). Bone morphogenetic protein-7 (BMP-7), growth/differentiation factor-5 (GDF-5) and NEL-like protein-1 (NELL-1), all known growth factors that stimulate bone formation, quantitatively accounted for the majority of the material obtained in all steps of isolation. Thus, cartilage serves as a store for growth factors. During initial bone formation septoclasts release osteoclastogenesis-stimulating factors deposited in non-calcified cartilage. Osteoclasts dissolve calcified cartilage and transport the released factors required for the stimulation of osteoprogenitor cells to deposit osteoid. High concentrations of BMP-7, GDF-5 and NELL-1 at the site of initial bone formation may suggest that their synergistic action favours osteogenesis.

Atelocollagen promotes chondrogenic differentiation of human adipose-derived mesenchymal stem cells

Effective engineering approaches for cartilage regeneration involve a combination of cells and biomaterial scaffolds. Multipotent mesenchymal stem cells (MSCs) are important sources for cartilage regeneration. Atelocollagen provides a suitable substrate for MSC attachment and enhancing chondrogenic differentiation. Here, we assessed the chondrogenic potential of adipose tissue derived human MSCs (hMSCs) mixed with atelocollagen gel. We observed cell attachment, viability, and microstructures by electron microscopy over 21 days. The levels of Sox9, type II collagen, aggrecan, type I collagen, Runx2, type X collagen, ALP, Osterix, and MMP13 were measured by RT-qPCR. Cartilage matrix-related proteins were assessed by enzyme-linked immunosorbent assay (ELISA), histology, and immunohistochemistry. hMSCs of all groups exhibited well-maintained cell survival, distribution and morphology. Abundant type II collagen fibers developed on day 21; while Sox9, type II collagen, and aggrecan expression increased over time in the atelocollagen group. However, type I collagen, RUNX2, type X collagen (CoL10A1), Osterix, and ALP were not expressed. These results corroborated the protein expression detected by ELISA. Further, histological analysis revealed lacunae-like structures, while staining demonstrated glycosaminoglycan accumulation. Cumulatively, these results indicate that atelocollagen scaffolds improve hMSC chondrogenic differentiation and are a potential approach for cartilage regeneration.

Characteristics of Neuropeptide-Containing Innervation, Tissue Remodeling, Growth, and Vascularity in Noses of Patients With Cleft Lip and Palate

OBJECTIVE

To detect the appearance and distribution of factors regulating remodeling, innervation, growth, and vascularity of the nasal tissue affected by cleft lip and palate (CLP).

DESIGN

Morphological analysis of human tissue.

SETTING

Cleft and craniofacial center.

PARTICIPANTS

Fifteen patients who underwent CLP rhinoplasty, 7 control patients.

INTERVENTIONS

Rhinoplasty.

MAIN OUTCOME MEASURES

Immunohistochemistry was performed with protein gene product (PGP) 9.5, transforming growth factor β1 (TGFβ1), vascular endothelial growth factor (VEGF), cluster of differentiation 34 (CD34), matrix metalloproteinase 2 (MMP2), MMP9, and tissue inhibitor of metalloproteinase 2 (TIMP2). The results were evaluated semiquantitatively. Spearman rank order correlation coefficient and Mann-Whitney U test were used for statistical analysis.

RESULTS

Cleft lip and palate-affected tissue revealed dense and loose connective tissue, adipose cells, and hyaline cartilage, along with numerous CD34-positive endotheliocytes and regions of VEGF-positive neoangiogenesis. We observed moderate to numerous PGP 9.5-positive nerve fibers. Transforming growth factor β1, MMP2, MMP9, and TIMP2 were found in cartilage and connective tissue. Cleft lip and palate-affected tissue compared to control samples showed a statistically significant difference in PGP 9.5 (P = .006), VEGF (P = .001), MMP2 (P = .002), MMP9 (P = .013), and TIMP2 (P < .001) expression. We observed a strong, positive correlation between VEGF and MMP9 (P = .027; r _S = 0.705).

CONCLUSIONS

The moderate expression of TGFβ1 and increased distribution of VEGF, MMP2, MMP9, and TIMP2 demonstrate an active extracellular matrix remodeling and angiogenesis, performed by proteases. The cartilaginous septum of the nose is an example of balance between tissue degradation and its suppression, demonstrated by the relationship between MMPs and TIMPs and the presence of VEGF.

Cartilage-gut-microbiome axis: a new paradigm for novel therapeutic opportunities in osteoarthritis

DNA of gut microbiota can be found in synovium of osteoarthritis and rheumatoid arthritis. This finding could result from the translocation of still alive bacteria from gut to joints through blood, since the diversified dormant microbiota of healthy human blood can be transiently resuscitated in vitro. The recent finding of gut microbiome in human cartilage, which differed between osteoarthritis and controls, suggests that a similar trafficking of dead or alive bacteria from gut microbiota physiologically occurs between gut and epiphysial bone marrow. Subchondral microbiota could enhance cartilage healing and transform components of deep cartilage matrix in metabolites with immunosuppressive properties. The differences of microbiome observed between hip and knee cartilage, either in osteoarthritis or controls, might be the counterpart of subtle differences in chondrocyte metabolism, themselves in line with differences in DNA methylation according to joints. Although bacteria theoretically cannot reach chondrocytes from the surface of intact cartilage, some bacteria enter the vascular channels of the epiphysial growth cartilage in young animals, whereas others can infect chondrocytes in vitro. In osteoarthritis, the early osteochondral plate angiogenesis may further enhance the ability of microbiota to locate close to the deeper layers of cartilage, and this might lead to focal dysbiosis, low-grade inflammation, cartilage degradation, epigenetic changes in chondrocytes and worsening of osteoarthritis. More studies on cartilage across different ethnic groups, weights, and according to age, are needed, to confirm the silent presence of gut microbiota close to human cartilage and better understand its physiologic and pathogenic significance.