Fabrication and properties of PLA/ß-TCP scaffolds using liquid crystal display (LCD) photocuring 3D printing for bone tissue engineering.

Introduction: Bone defects remain a thorny challenge that clinicians have to face. At present, scaffolds prepared by 3D printing are increasingly used in the field of bone tissue repair. Polylactic acid (PLA) has good thermoplasticity, processability, biocompatibility, and biodegradability, but the PLA is brittle and has poor osteogenic performance. Beta-tricalcium phosphate (ß-TCP) has good mechanical properties and osteogenic induction properties, which can make up for the drawbacks of PLA. Methods: In this study, photocurable biodegradable polylactic acid (bio-PLA) was utilized as the raw material to prepare PLA/ß-TCP slurries with varying ß-TCP contents (ß-TCP dosage at 0%, 10%, 20%, 30%, 35% of the PLA dosage, respectively). The PLA/ß-TCP scaffolds were fabricated using liquid crystal display (LCD) light-curing 3D printing technology. The characterization of the scaffolds was assessed, and the biological activity of the scaffold with the optimal compressive strength was evaluated. The biocompatibility of the scaffold was assessed through CCK-8 assays, hemocompatibility assay and live-dead staining experiments. The osteogenic differentiation capacity of the scaffold on MC3T3-E1 cells was evaluated through alizarin red staining, alkaline phosphatase (ALP) detection, immunofluorescence experiments, and RT-qPCR assays. Results: The prepared scaffold possesses a three-dimensional network structure, and with an increase in the quantity of ß-TCP, more ß-TCP particles adhere to the scaffold surface. The compressive strength of PLA/ß-TCP scaffolds exhibits a trend of initial increase followed by decrease with an increasing amount of ß-TCP, reaching a maximum value of 52.1 MPa at a 10% ß-TCP content. Degradation rate curve results indicate that with the passage of time, the degradation rate of the scaffold gradually increases, and the pH of the scaffold during degradation shows an alkaline tendency. Additionally, Live/dead staining and blood compatibility experiments suggest that the prepared PLA/ß-TCP scaffold demonstrates excellent biocompatibility. CCK-8 experiments indicate that the PLA/ß-TCP group promotes cell proliferation, and the prepared PLA/ß-TCP scaffold exhibits a significant ability to enhance the osteogenic differentiation of MC3T3-E1 cells in vitro. Discussion: 3D printed LCD photocuring PLA/ß-TCP scaffolds could improve surface bioactivity and lead to better osteogenesis, which may provide a unique strategy for developing bioactive implants in orthopedic applications.

[Preparation of berberine-naringin dual drug-loaded composite microspheres and evaluation of their antibacterial-osteogenic properties].

Objective: To develop a drug-loaded composite microsphere that can simultaneously release the berberine (BBR) and naringin (NG) to repair infectious bone defects. Methods: The NG was loaded on mesoporous microspheres (MBG) to obtain the drug-loaded microspheres (NG-MBG). Then the dual drug-loaded compound microspheres (NG-MBG@PDA-BBR) were obtained by wrapping NG-MBG with polydopamine (PDA) and modifying the coated PDA with BBR. The composite microspheres were characterized by scanning electron microscopy, X-ray diffraction, specific surface area and pore volume analyzer, and Fourier transform infrared spectroscopy; the drug loading rate and release of NG and BBR were measured; the colony number was counted and the bacterial inhibition rate was calculated after co-culture with Staphylococcus aureus and Escherichia coli for 12 hours to observe the antibacterial effect; the biocompatibility was evaluated by live/dead cell fluorescence staining and cell counting kit 8 assay after co-culture with rat's BMSCs for 24 and 72 hours, respectively, and the osteogenic property was evaluated by alkaline phosphatase (ALP) staining and alizarin red staining after 7 and 14 days, respectively. Results: NG-MBG@PDA-BBR and three control microspheres (MBG, MBG@PDA, and NG-MBG@PDA) were successfully constructed. Scanning electron microscopy showed that NG-MBG@PDA-BBR had a rough lamellar structure, while MBG had a smooth surface, and MBG@PDA and NG-MBG@PDA had a wrapped agglomeration structure. Specific surface area analysis showed that MBG had a mesoporous structure and had drug-loading potential. Low angle X-ray diffraction showed that NG was successfully loaded on MBG. The X-ray diffraction pattern contrast showed that all groups of microspheres were amorphous. Fourier transform infrared spectroscopy showed that NG and BBR peaks existed in NG-MBG@PDA-BBR. NG-MBG@PDA-BBR had good sustained drug release ability, and NG and BBR had early burst release and late sustained release. NG-MBG@PDA-BBR could inhibit the growth of Staphylococcus aureus and Escherichia coli, and the antibacterial ability was significantly higher than that of MBG, MBG@PDA, and NG-MBG@PDA ( P<0.05). But there was a significant difference in biocompatibility at 72 hours among microspheres ( P<0.05). ALP and alizarin red staining showed that the ALP positive area and the number of calcium nodules in NG-MBG@PDA-BBR were significantly higher than those of MBG and NG-MBG ( P<0.05), and there was no significant difference between NG-MBG@PDA and NG-MBG@PDA ( P>0.05). Conclusion: NG-MBG@PDA-BBR have sustained release effects on NG and BBR, indicating that it has ideal dual performance of osteogenesis and antibacterial property.

Direct osteogenesis and immunomodulation dual function via sustained release of naringin from the polymer scaffold.

Many traditional Chinese medicine monomers, such as naringin (NG), can regulate the local immune microenvironment to benefit osteogenesis. However, the rapid release of NG from scaffolds severely influences the osteogenesis-promoting effect. Herein, NG was loaded into mesoporous bioglass (MBG) to achieve sustained release through physical adsorption and the barrier role of mesoporous channels, then MBG loaded with NG was added to poly(L-lactic acid) (PLLA) to fabricate composite scaffolds by selective laser sintering (SLS) technology. The results showed that the NG-MBG/PLLA scaffolds could continuously and slowly release NG for 14 days compared with NG/PLLA scaffolds, and the cumulative release amount for the NG-MBG/PLLA scaffolds was 44.26%. In addition, the NG-MBG/PLLA scaffolds can promote the proliferation and osteogenesis differentiation of mouse bone marrow mesenchymal stem cells (mBMSCs). Meanwhile, the composite scaffolds decreased the reactive oxygen species (ROS) level of RAW264.7 under the stimulation of lipopolysaccharide (LPS) and significantly suppressed interleukin-6 (IL-6) and enhanced arginase-1 (Arg-1) protein expressions. Moreover, calcium nodule and alkaline phosphatase production of mBMSCs in a macrophage-conditioned medium for the NG-MBG/PLLA group also evidently increased compared with the PLLA and MBG/PLLA groups. These NG sustained-release composite scaffolds with osteo-immunomodulation function have great application prospects in the clinic.

Ternary regulation mechanism of Rhizoma drynariae total flavonoids on induced membrane formation and bone remodeling in Masquelet technique.

CONTEXT: Rhizoma drynariae total flavonoids (RDTF) are used to treat fractures. CD31hiEmcnhi vessels induced by PDGF-BB secreted by osteoclast precursors, together with osteoblasts and osteoclasts, constitute the ternary regulatory mechanism of bone tissue reconstruction. OBJECTIVE: This study aimed to determine whether RDTF can promote bone tissue remodeling and induce membrane growth in the rat Masquelet model and to explore its molecular mechanism based on the ternary regulation theory. METHODS: Thirty-six SD rats were randomized to three groups: blank, induced membrane, and RDTF treatment (n = 12/group). The gross morphological characteristics of the new bone tissue were observed after 6 weeks. Sixty SD rats were also randomized to five groups: blank, induction membrane, low-dose RDTF, medium-dose RDTF, and high-dose RDTF (n = 12/group). After 4 weeks, immunohistochemistry and western blot were used to detect the expression of membrane tissue-related proteins. The mRNA expression of key factors of ternary regulation was analyzed by qRT-PCR. RESULTS: RDTF positively affected angiogenesis and bone tissue reconstruction in the bone defect area. RDTF could upregulate the expression of key factors (PDGF-BB, CD31, and endomucin), VEGF, and HMGB1 mRNA and proteins in the ternary regulation pathway. DISCUSSION AND CONCLUSION: Although the expected CD31hiEmcnhi vessels in the induction membrane were not observed, this study confirmed that RDTF could promote the secretion of angiogenic factors in the induced membrane. The specific mechanisms still need to be further studied.

Is percutaneous pinning needed for the treatment of displaced distal radius metaphyseal fractures in children?: A systematic review.

BACKGROUND: Distal radius metaphyseal (DRM) fractures are very frequent childhood fractures. Whether additional percutaneous pinning improves the outcome remains controversial. In this review, we tried to systematically evaluate the effect of percutaneous pinning on re-displacement, secondary reduction, radiographs, function, and complications in children with displaced DRM fractures. METHODS: PubMed, Medline, Embase, Cochrane Library, and Web of Science databases were explored systematically to identify randomized controlled trials (RCTs) and clinical controlled trials (CCTs) comparing cast immobilization alone or following reduction to additional percutaneous pinning in the treatment of pediatric displaced DRM fractures. Two reviewers independently screened eligible articles and extracted relevant information from each article. The methodological quality of eligible articles was evaluated using the Cochrane Collaboration risk assessment tool (RCTs) and modified Jadad scale (CCTs). RESULTS: A total of 4 RCTs and 3 CCTs met the inclusion criteria, with a total patient count of 1144 children. The results showed that additional percutaneous pinning significantly reduced the rate of re-placement (Chi-square tests, P < .001) and complications (Chi-square tests, P = .030). The superior results, both radiographically and functionally seemed to be temporary. No difference was found between the 2 groups after longer-term follow-up. CONCLUSIONS: This systematic review suggested that compared with casting following reduction, percutaneous pinning had a positive effect on maintaining the initial reduction and reducing fracture complication rate of displaced DRM fractures in children, but with no significant improvement in function and radiographic outcome at the long-term follow-up. We suggest clinicians think twice before percutaneous pinning of displaced pediatric DRM fractures.

MiR-214 is an important regulator of the musculoskeletal metabolism and disease.

MiR-214 belongs to a family of microRNA (small, highly conserved noncoding RNA molecules) precursors that play a pivotal role in biological functions, such as cellular function, tissue development, tissue homeostasis, and pathogenesis of diseases. Recently, miR-214 emerged as a critical regulator of musculoskeletal metabolism. Specifically, miR-214 can mediate skeletal muscle myogenesis and vascular smooth muscle cell proliferation, migration, and differentiation. MiR-214 also modulates osteoblast function by targeting specific molecular pathways and the expression of various osteoblast-related genes; promotes osteoclast activity by targeting phosphatase and tensin homolog (Pten); and mediates osteoclast-osteoblast intercellular crosstalk via an exosomal miRNA paracrine mechanism. Importantly, dysregulation in miR-214 expression is associated with pathological bone conditions such as osteoporosis, osteosarcoma, multiple myeloma, and osteolytic bone metastasis of breast cancer. This review discusses the cellular targets of miR-214 in bone, the molecular mechanisms governing the activities of miR-214 in the musculoskeletal system, and the putative role of miR-214 in skeletal diseases. Understanding the biology of miR-214 could potentially lead to the development of miR-214 as a possible biomarker and a therapeutic target for musculoskeletal diseases.

[Research progress on induced membrane technique for the treatment of segmental bone defect].

Treatment of large bone defects caused by trauma, osteomyelitis, and tumors has been a major challenge in clinical. In the past, there have been many ways to repair and reconstruct the large bone defects. However, there is a long period of treatment, high technical requirement and complications such as ununion. After Masquelet reported the induced membrane technology in 2000, the technique was widely used in treatment of trauma, osteomyelitis, and large bone defects caused by tumors. It has been obtained good results. It has the advantages of short course, high healing rate, easy operation and easy to master. The induced membrane has unique structural characteristics and biological characteristics. There are many kinds of osteogenic factors that are included in the membrane, such as vascular endothelial growth factor, and morphogenetic protein-2, transforming growth factor-ß1, etc. These osteogenic factors contribute to accelerate bone healing. With the development of induced membrane technology. The technology of Reamer Irrigator Aspirator technology, engineering tissue technology and internal fixation is used in clinic.It can provide bone source, promote bone defect reconstruction, improve long-term limb function and reduce complications.This paper retrospectively summarizes the experimental research and clinical progress of Masquelet technique in the treatment of large bone defects.

Minimally invasive versus extensile lateral approach for sanders type II and III calcaneal fractures: A meta-analysis of randomized controlled trials.

BACKGROUND: The use of less-invasive techniques in the treatment of displaced intra-articular calcaneal fractures (DIACFs) remains controversial. No prior meta-analysis has considered the influence of differences in the fracture type. Thus, our meta-analysis aimed to investigate the efficacy and safety of minimally invasive (MI) in Sanders type II and III fractures. MATERIALS AND METHODS: A comprehensive search was performed to identify RCTs comparing MI using sinus tarsi approach (STA) or percutaneous reduction (PR) to open reduction (OR) via extensile lateral approach (ELA) from the Cochrane Library, PubMed, Embase and CNKI. Dichotomous and continuous data were pooled using risk ratio (RR) and mean difference (MD), respectively, with 95% confidence intervals (CIs). The data were analysed using Review Manager 5.3. RESULTS: Eight RCTs (495 participants) were selected in our meta-analysis. Based on the American Orthopaedic Foot and Ankle Society score (AOFAS), both general pooled data and subgroup analysis of Sanders type II fractures indicated that MI improves functional outcomes, while in the Sanders type III subgroup, the advantage disappeared. Additionally, the pooled results showed that MI reduces the rate of wound complications; lowers the VAS score; and shortens the time to surgery, duration of surgery and length of hospital stay. There was no statistical significance with respect to recovery of calcaneus length and width or improvement of Gissane's angle and Bohler's angle. CONCLUSION: Our meta-analysis suggests that MI and ELA are equally effective treating Sanders type II and III fractures. However, MI is effective in improving the AOFAS score (Sanders type II); reducing the rate of wound complications; and shortening the time to surgery, duration of surgery and length of hospital stay.