An immunomodulatory and osteogenic bacterial cellulose scaffold for bone regeneration via regulating the immune microenvironment.

Creating a bone homeostasis microenvironment that balances osteogenesis and immunity is a substantial challenge for bone regeneration. Here, we prepared an immunomodulatory and osteogenic bacterial cellulose scaffold (FOBS) via a facile one-pot approach. The aldehyde groups were generated via selective oxidation of the hydroxyl groups of bacterial cellulose, offering the bonding sites for dopamine through a Schiff base reaction. At the same time, the deposition of Ca2+ and PO43- was promoted on the aldehyde cellulose scaffold because of the high affinity of the catechol moiety for Ca2+. Compared with that of the unmodified scaffold, the hydroxyapatite content of FOBS increased by 47.1 % according to the ICP results. Interestingly, FOBS regulated the immune microenvironment to accelerate the conversion of M1 to M2 macrophages. The expressions of ARG-1 and Dectin-1 (M2) in the FOBS group increased by >100 %. The expression of osteogenic differentiation of BMSCs was also upregulated. In a rat cranial defect model, the BV/TV of FOBS was significantly increased. Further immunohistochemical analysis revealed that an improved immune microenvironment promoted the osteogenic differentiation of stem cells in vivo. This work provides an effective and easy-to-operate strategy for the development of the bone tissue engineering scaffolds.

ECM-inspired calcium/zinc laden cellulose scaffold for enhanced bone regeneration.

Cellulose-based polymer scaffolds are highly diverse for designing and fabricating artificial bone substitutes. However, realizing the multi-biological functions of cellulose-based scaffolds has long been challenging. In this work, inspired by the structure and function of the extracellular matrix (ECM) of bone, we developed a novel yet feasible strategy to prepare ECM-like scaffolds with hybrid calcium/zinc mineralization. The 3D porous structure was formed via selective oxidation and freeze drying of bacterial cellulose. Following the principle of electrostatic interaction, calcium/zinc hybrid hydroxyapatite nucleated, crystallized, and precipitated on the 3D scaffold in simulated physiological conditions, which was well confirmed by morphology and composition analysis. Compared with alternative scaffold cohorts, this hybrid ion-loaded cellulose scaffold exhibited a pronounced elevation in alkaline phosphatase (ALP) activity, osteogenic gene expression, and cranial defect regeneration. Notably, the hybrid ion-loaded cellulose scaffold effectively fostered an M2 macrophage milieu and had a strong immune effect in vivo. In summary, this study developed a hybrid multifunctional cellulose-based scaffold that appropriately simulates the ECM to regulate immunomodulatory and osteogenic differentiation, setting a measure for artificial bone substitutes.

Chylothorax following posterior low lumbar fusion surgery: A case report.

BACKGROUND: Postoperative chylothorax is usually regarded as a complication associated with cardiothoracic surgery; however, it is one of the rare complications in orthopedic surgery. This case report describes a female patient who developed chylothorax after a successful L4-S1 transforaminal lumbar interbody fusion surgery. The etiology, diagnosis, and treatment were analyzed and discussed. CASE SUMMARY: A 50-year-old woman was admitted with repeated back and leg pain. She was diagnosed with L4 degenerative spondylolisthesis, L4/L5 and L5/S1 intervertebral disc herniation and L5 instability, and underwent successful posterior L4-S1 instrumentation and fusion surgery. Unfortunately, thoracic effusion was identified 2 d after operation. The thoracic effusion was finally confirmed to be chylous based on twice positive chyle qualitative tests. The patient was discharged after 12-d persisting drainage, 3-d total parenteral nutrition and fasting, and other supportive treatments. No recurring symptoms were observed within 12 mo follow-up. CONCLUSION: Differential diagnosis is crucial for unusual thoracic effusion. Comprehensive diagnosis and treatment of chylothorax are necessary. Thorough intraoperative protection to relieve high thoracic pressure caused by the prone position is important.