The chondrocyte channelome: A narrative review

Chondrocytes are the main cells in the extracellular matrix (ECM) of articular cartilage and possess a highly differentiated phenotype that is the hallmark of the unique physiological functions of this specialised load-bearing connective tissue. The plasma membrane of articular chondrocytes contains a rich and diverse complement of membrane proteins, known as the membranome, which defines the cell surface phenotype of the cells. The membranome is a key target of pharmacological agents and is important for chondrocyte function. It includes channels, transporters, enzymes, receptors, and anchors for intracellular, cytoskeletal and ECM proteins and other macromolecular complexes. The chondrocyte channelome is a sub-compartment of the membranome and includes a complete set of ion channels and porins expressed in these cells. Many of these are multi-functional proteins with “moonlighting” roles, serving as channels, receptors and signalling components of larger molecular assemblies. The aim of this review is to summarise our current knowledge of the fundamental aspects of the chondrocyte channelome, discuss its relevance to cartilage biology and highlight its possible role in the pathogenesis of osteoarthritis (OA). Excessive and inappropriate mechanical loads, an inflammatory micro-environment, alternative splicing of channel components or accumulation of basic calcium phosphate crystals can result in an altered chondrocyte channelome impairing its function. Alterations in Ca²⁺ signalling may lead to defective synthesis of ECM macromolecules and aggravated catabolic responses in chondrocytes, which is an important and relatively unexplored aspect of the complex and poorly understood mechanism of OA development.     

Optimization of immunohistochemical detection of collagen type II in osteochondral sections by comparing decalcification and antigen retrieval agent combinations

Bone containing tissues such as osteochondral joint are resistant to routine tissue processing, therefore require decalcification. This technique causes removal of mineral salts, but in the process may macerate the organic tissue, hence the need for tissue fixation. Such severe processing demands careful antigen retrieval to necessitate optimal staining. The aim of our study was to compare five different antigen retrieval protocols (heat retrieval and protein digestion) following decalcification of rabbit knee joints using two different techniques (20% formic acid and 10% ethylenediamine-tetra acetic acid: EDTA). Osteochondral sections were compared based on time required for decalcification, ease of sectioning, morphological integrity using HE staining and antigen preservation (Collagen type II) using immunohistochemistry. The two decalcification solutions did not impair the tissue morphology and ease of sectioning. Joints processed with formic acid decalcified four times faster than EDTA. Among the five antigen retrieval approaches, maximal collagen II uptake with minimal nonspecific staining was found with protein digestion (pronase and hyaluronidase) in both formic acid and EDTA sections. For osteo-chondral sections, we recommend using 10% EDTA for decalcification and pronase plus hyaluronidase for antigen retrieval if maintaining tissue morphology is crucial, whereas if time is of the essence, 20% FA with pronase plus hyaluronidase is the faster option while still preserving structural integrity. Clin. Anat. 33:343–349, 2020. © 2019 Wiley Periodicals, Inc.     

环状软骨前裂开对兔环状软骨生长发育的影响

目的:观察环状软骨前裂开对环状软骨生长发育的影响。方法:将幼兔环状软骨前正中裂开,8月后测量环状软骨内径,计算其管腔面积。结果:(1)与对照组比较,实验组兔环状软骨管腔面积无显著性差异(P>0.05)。(2)裂开处均由软组织连接,未形成过多瘢痕。结论:环状软骨前裂开对环状软骨及动物的生长发育无明显影响。     

Membrane-seeded autologous chondrocytes: cell viability and characterization at surgery

The implantation of chondrocytes, seeded on matrices such as hyaluronic acid or collagen membranes, is a method that is being widely used for the treatment of chondral defects. The aim of the present study was to evaluate the distribution, viability and phenotype expression of the cells seeded on a collagen membrane just at the time of the implantation. Twelve patients who were suffering from articular cartilage lesions were treated by the MACI^® procedure. The residual part of each membrane was tested by colorimetric assay (MTT) and histochemical and ultrastructural analyses were carried out. In all of the samples a large number of viable cells, quite homogenously distributed, was detected. The cells expressed the markers of the differentiated hyaline chondrocytes. These data reassure in that the MACI procedure provides a suitable engineered tissue for cartilage repair, in line with the clinical evidences emerging in the literature.     

骨髓基质干细胞修复兔关节软骨缺损的实验研究

目的研究以多聚乙醇酸(PGA)为支架的骨髓基质干细胞(BMSCs)复合物修复兔膝关节软骨缺损的情况。方法体外培养扩增的自体BMSCs种植于PGA支架并培养72h,然后将支架-细胞复合物植入兔关节软骨缺损模型。术后12周处死动物,标本行大体观察、组织学检查及Ⅱ型胶原免疫组化染色。结果BMSCs-PGA复合物植入后形成丰富的透明软骨样修复组织,新生软骨无明显退变。对照组主要为纤维组织及软骨下骨修复。结论BMSCs-PGA复合物可修复关节软骨缺损。     

The remucosalizing alar cartilage flap: a reconstructive option for repairing nasal septal perforations

The objective of this study is to assess the results of repairing septal perforations with a vascularized pedicled alar cartilage island flap. Using the external rhinoplasty approach, a vascularized flap of alar cartilage, harvested as a cephalic trim and pedicled on the ascending columellar branches of the superior labial artery was raised. Bilateral mucoperichondrial septal flaps were elevated and the alar flap was transposed and secured within the defect and bilaterally overlaid with temporalis fascia. Silastic sheets were placed and remained in situ until the grafts were revascularized from the peripheries of the defect as well as centrally from the alar flap. The revascularized temporalis fascia acted as a scaffold for nasal remucosalization. The alar flap also increased the long-term structural robustness of the repair. Between 1999 and 2003, 14 patients with septal perforations ranging from 10 to 31 mm underwent septal reconstruction using this technique. There were nine males and five females. The flap was successfully raised in all cases and long-term closure was maintained in 12 patients (86%). The alar cartilage flap is an effective technique for repairing septal perforations in selected patients. It provides vascularized tissue which nourishes the grafts during remucosalization, and a cartilaginous framework, which affords long-term structural support to the repair. It also obviates the need to transpose nasal mucosa and create a secondary defect. The rhinoplasty approach furthermore permits additional nasal deformities to be corrected at the same time. Presented at the British Association of Plastic Surgeons Summer Scientific Meeting, Sheffield, UK (12 July 2006).     

SCP对人乳腺癌细胞增殖抑制作用的研究

目的：研究SCP对人乳腺癌细胞生长，抑制效应，探讨其抗癌作用机制。方法：用不同浓度的SCP加入体外培养的人乳腺癌细胞（MCF－7）中，观察加药后细胞生长和有丝分裂指数（MI）的变化，用MTT法检测其细胞毒作用；Hoechst33342/PI荧光双染色方法检测细胞凋亡。结果：SCP明显抑制MCF－7细胞生长，IC50值为1mg/ml;MI于加药后48h较对照组明显降低；凋亡细胞比例在用药后48h达63．3％，结论：SCP可有效抑制人乳腺癌细胞的增殖。     

胚胎颅骨骨膜移植修复髋关节软骨大面积缺损

１９９０年５月～１９９４年４月，对４２例（４７个髋）关节软骨全厚缺损患者采用冷冻保存胚胎颅骨骨膜移植进行修复，其中１４例股骨头骨质Ⅳ期坏死者，同时施行带旋髂深血管蒂髂骨植骨。对３４例（３８个髋）进行了２年～６年（平均４０个月）随访。结果表明，按照吴之康髋关节人工置换术后疗效评定标准，优良２５例，很好５例，好３例，尚可１例。认为，与自体移植物修复关节软骨大面积缺损相比，这种方法无附加损伤，具有移植材料、形态与股骨头相似等特点，是治疗髋关节软骨大面积缺损的一种有效方法。