Local modulation of the Wnt/β-catenin and bone morphogenic protein (BMP) pathways recapitulates rib defects analogous to cerebro-costo-mandibular syndrome

Enhancing Calcium Phosphate Cements: A review of Bacterial Cellulose (BC) and other Biopolymer Reinforcements for Biomedical Applications

Calcium phosphate cements (CPCs) are renowned for their biocompatibility and osteoconductivity, making them ideal for bone tissue engineering. However, their brittleness and low tensile strength limit their use in load-bearing applications. Bacterial cellulose (BC) has emerged as a promising reinforcement material due to its high tensile strength, biocompatibility, and biodegradability. The incorporation of 2 wt% BC into CPCs increased compressive strength from 5 MPa to 12 MPa, representing a 2.4-fold enhancement, while also improving toughness and promoting cellular interactions through its nanofibrillar structure. Additionally, hybrid composites combining BC with collagen, chitosan, or polycaprolactone (PCL) exhibit synergistic effects, further enhancing mechanical properties and biodegradability. These advancements highlight the potential of BC-reinforced CPCs for clinical applications in bone repair and regeneration. Despite these improvements, limited research addresses tensile and flexural properties, which are critical for load-bearing applications, as well as the effects of BC on injectability and setting time for minimally invasive procedures. Emerging innovations, such as electroactive BC-reinforced CPCs for stimulating bone healing, hold significant potential but remain underexplored. Future research should focus on optimising mechanical properties, validating clinical performance, and developing hybrid formulations to expand their use in load-bearing bone repairs.

A Newborn with Extremely Rare Cerebro-Costo-Mandibular Syndrome; A Case Report Study

BACKGROUND

Cerebro-costo-mandibular syndrome (CCMS) is a rare congenital syndrome consisting of the main features of micrognathia and posterior rib gaps. Due to multiple abnormalities, patients almost have difficulty breathing with upper airway obstruction, decreased thoracic capacity, spina bifida, and scoliosis.

CASE PRESENTATION

We describe a case of a late preterm neonate boy presenting with low Apgar, respiratory distress, and complicated orofacial anomalies that had a poor outcome. His radiographic findings showed mandibular hypoplasia (micrognathia), chest deformity, multiple posterior rib gap defects, and abnormal costotransverse articulation. Based on physical examination and radiologic findings, the diagnosis of CCMS confirmed for the patient.

CONCLUSION

Physicians should always consider the diagnosis of CCMS in all infants with micrognathia and rib-gap defects. These infants need careful respiratory function monitoring. Early airway management improves growth and development. In addition, their physical and psychological development should be assessed regularly.

Defects of the spliceosomal gene SNRPB affect osteo- and chondro-differentiation

Although gene splicing occurs throughout the body, the phenotype of spliceosomal defects is largely limited to specific tissues. Cerebro-costo-mandibular syndrome (CCMS) is one such spliceosomal disease, which presents as congenital skeletal dysmorphism and is caused by mutations of SNRPB gene encoding Small Nuclear Ribonucleoprotein Polypeptides B/B' (SmB/B'). This study employed in vitro cell cultures to monitor osteo- and chondro-differentiation and examined the role of SmB/B' in the differentiation process. We found that low levels of SmB/B' by knockdown or mutations of SNRPB led to suppressed osteodifferentiation in Saos-2 osteoprogenitor-like cells, which was accompanied by affected splicing of Dlx5. On the other hand, low SmB/B' led to promoted chondrogenesis in HEPM mesenchymal stem cells. Consistent with other reports, osteogenesis was promoted by the Wnt/β-catenin pathway activator and suppressed by Wnt and BMP blockers, whereas chondrogenesis was promoted by Wnt inhibitors. Suppressed osteogenic markers by SNRPB knockdown were partly rescued by Wnt/β-catenin pathway activation. Reporter analysis revealed that suppression of SNRPB results in attenuated Wnt pathway and/or enhanced BMP pathway activities. SNRPB knockdown altered splicing of TCF7L2 which impacts Wnt/β-catenin pathway activities. This work helps unravel the mechanism underlying CCMS whereby reduced expression of spliceosomal proteins causes skeletal phenotypes.

Non-ubiquitous expression of core spliceosomal protein SmB/B' in chick and mouse embryos

BACKGROUND

Although splicing is an integral part of the expression of many genes in our body, genetic syndromes with spliceosomal defects affect only specific tissues. To help understand the mechanism, we investigated the expression pattern of a core protein of the major spliceosome, SmB/B' (Small Nuclear Ribonucleoprotein Polypeptides B/B'), which is encoded by SNRPB. Loss-of-function mutations of SNRPB in humans cause cerebro-costo-mandibular syndrome (CCMS) characterized by rib gaps, micrognathia, cleft palate, and scoliosis. Our expression analysis focused on the affected structures as well as non-affected tissues, using chick and mouse embryos as model animals.

RESULTS

Embryos at young stages (gastrula) showed ubiquitous expression of SmB/B'. However, the level and pattern of expression became tissue-specific as differentiation proceeded. The regions relating to CCMS phenotypes such as cartilages of ribs and vertebrae and palatal mesenchyme express SmB/B' in the nucleus sporadically. However, cartilages that are not affected in CCMS also showed similar expressions. Another spliceosomal gene, SNRNP200, which mutations cause retinitis pigmentosa, was also prominently expressed in cartilages in addition to the retina.

CONCLUSION

The expression of SmB/B' is spatiotemporally regulated during embryogenesis despite the ubiquitous requirement of the spliceosome, however, the expression pattern is not strictly correlated with the phenotype presentation.

Relationship between BMP2/9 Levels and Spinal Function and Quality of Life in Patients with Severe Scoliosis after PVCR

Objective

To explore the relationship between (bone fusion associated protein) bone morphogenetic protein (BMP)2 and BMP9 and spinal function and quality of life in patients with severe scoliosis after posterior vertebral column resection (PVCR).

Methods

78 cases of severe scoliosis treated with PVCR surgery in our hospital from January 2015 to April 2018 were selected and set as the observation group, and 80 health examiners in the same period were selected and set as the control group. The ELISA method was used to detect the levels of BMP2 and BMP9 in the two groups. Also, the relationship between the recovery of spinal function, quality of life, and serum BMP2 and BMP9 in the observation group was analyzed. The receiver operating characteristic curve was used to evaluate the predictive value of BMP2 and BMP9 for complications after PVCR.

Results

One month after PVCR, the serum BMP2 and BMP9 levels of patients with severe scoliosis were higher than those of healthy people (P < 0.05). One year after PVCR, Pearson correlation analysis showed that serum levels of BMP2 and BMP9 in patients with scoliosis were positively correlated with ODI scores (r = 0.778, P < 0.001; r = 0.746, P < 0.001), SRS-22 scores (r = 0.758, P < 0.001; r = 0.722, P < 0.001), and Cobb angle correction rate (r = 0.838, P < 0.001; r = 0.802, P < 0.001).

Conclusion

The levels of BMP2 and BMP9 of patients with scoliosis after PVCR are higher than those of healthy people. After 1-year follow-up, the patients' serum BMP2 and BMP9 levels were positively correlated with spinal function recovery, quality of life, and surgical efficacy. Among them, BMP2 and BMP9 had the highest correlation with PVCR surgical efficacy. Paying attention to the serum BMP2 and BMP9 levels of patients with scoliosis has certain clinical significance.

MicroRNA-27b targets CBFB to inhibit differentiation of human bone marrow mesenchymal stem cells into hypertrophic chondrocytes

Background

Human bone marrow-derived mesenchymal stem cells (hBMSCs) have chondrocyte differentiation potential and are considered to be a cell source for cell-transplantation-mediated repair of cartilage defects, including those associated with osteoarthritis (OA). However, chondrocyte hypertrophic differentiation is a major obstacle for the application of hBMSCs in articular cartilage defect treatment. We have previously shown that microRNA-27b (miR-27b) inhibits hypertrophy of chondrocytes from rat knee cartilage. In this study, we investigated the role of miR-27b in chondrocyte hypertrophic differentiation of hBMSCs.

Methods

Chondrogenic marker and microRNA expression in hBMSC chondrogenic pellets were evaluated using RT-qPCR and immunohistochemistry. The hBMSCs were transfected with miR-27b before inducing differentiation. Gene and protein expression levels were analyzed using RT-qPCR and western blot. Coimmunoprecipitation was used to confirm interaction between CBFB and RUNX2. Luciferase reporter assays were used to demonstrate that CBFB is a miR-27b target. Chondrogenic differentiation was evaluated in hBMSCs treated with shRNA targeting CBFB. Chondrogenic hBMSC pellets overexpressing miR-27b were implanted into cartilage lesions in model rats; therapeutic effects were assessed based on histology and immunohistochemistry.

Results

The hBMSCs showed typical MSC differentiation potentials. During chondrogenic differentiation, collagen 2 and 10 (COL2 and COL10), SOX9, and RUNX2 expression was upregulated. Expression of miR-140, miR-143, and miR-181a increased over time, whereas miR-27b and miR-221 were downregulated. Cartilage derived from hBMSC and overexpressing miR-27b exhibited higher expression of COL2 and SOX9, but lower expression of COL10, RUNX2, and CBFB than did the control cartilage. CBFB and RUNX2 formed a complex, and CBFB was identified as a novel miR-27b target. CBFB knockdown by shRNA during hBMSC chondrogenic differentiation led to significantly increased COL2 and SOX9 expression and decreased COL10 expression. Finally, miR-27b-overexpressing hBMSC chondrogenic pellets had better hyaline cartilage morphology and reduced expression of hypertrophic markers and tend to increase repair efficacy in vivo.

Conclusion

MiR-27b plays an important role in preventing hypertrophic chondrogenesis of hBMSCs by targeting CBFB and is essential for maintaining a hyaline cartilage state. This study provides new insights into the mechanism of hBMSC chondrocyte differentiation and will aid in the development of strategies for treating cartilage injury based on hBMSC transplantation.