The exosomal secretomes of mesenchymal stem cells extracted via 3D-printed lithium-doped calcium silicate scaffolds promote osteochondral regeneration.

The development of surface modification techniques has brought about a major paradigm shift in the clinical applications of bone tissue regeneration. Biofabrication strategies enable the creation of scaffolds with specific microstructural environments and biological components. Lithium (Li) has been reported to exhibit anti-inflammatory, osteogenic, and chondrogenic properties by promoting several intracellular signaling pathways. Currently, research focuses on fabricating scaffolds with simultaneous dual bioactivities to enhance osteochondral regeneration. In this study, we modified the surface of calcium silicate (CS) scaffolds with Li using a simple immersion technique and evaluated their capabilities for bone regeneration. The results showed that Li ions could be easily coated onto the surfaces of CS scaffolds without affecting the microstructural properties of CS itself. Furthermore, the modifications did not affect the printing capabilities of the CS, and porous scaffolds could be fabricated via extrusion. Moreover, the presence of Li improved the surface roughness and hydrophilicity, thus leading to enhanced secretion of osteochondral-related regeneration factors, such as alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen II (Col II) proteins. Subsequent in vivo studies, including histological and micro-CT analyses, confirmed that the Li-modified CS scaffolds promoted osteochondral regeneration. The transcriptome analysis suggested that the enhanced osteochondrogenic capabilities of our scaffolds were influenced by paracrine exosomes. We hope this study will inspire further research on osteochondral regeneration.

Correction: Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells.

Correction for 'Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells' by Yung-Cheng Chiu et al., J. Mater. Chem. B, 2023, 11, 4666-4676, https://doi.org/10.1039/D3TB00208J.

Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells.

3D-printed scaffolds are suitable for patient-specific implant preparation for bone regeneration in large-scale critical bone defects. In addition, these scaffolds should have mechanical and biological properties similar to those of natural bone tissue. In this study, 3D-printed barium-doped calcium silicate (BaCS)/poly-ε-caprolactone (PCL) composite scaffolds were fabricated as an alternative strategy for bone tissue engineering to achieve appropriate physicochemical characteristics and stimulate osteogenesis. Scaffolds containing 10% Ba (Ba10) showed optimal mechanical properties, preventing premature scaffold degradation during immersion while enabling ion release in a sustained manner to achieve the desired therapeutic goals. In addition, Wharton's jelly mesenchymal stem cells (WJMSCs) were used to assess biocompatibility and osteogenic differentiation behaviour. WJMSCs were cultured on the scaffold and permeabilised via ICP to analyse the presence of Si and Ba ions in the medium and cell lysates, suggesting that the ions released by the scaffold could effectively enter the cells. The protein expression of CaSR, PI3K, Akt, and JNK confirmed that CaSR could activate cells cultured in Ba10, thereby affecting the subsequent PI3k/Akt and JNK pathways and further promoting osteogenic differentiation. The in vivo performance of the proposed scaffolds was assessed using micro-CT and histological slices, which revealed that the BaCS scaffolds could further enhance bone regeneration, compared with bare scaffolds. These results suggest the potential use of 3D-printed BaCS/PCL scaffolds as next-generation substitutes for bone regeneration.

Plasma cell-free DNA promise monitoring and tissue injury assessment of COVID-19.

Coronavirus 2019 (COVID-19) is a complex disease that affects billions of people worldwide. Currently, effective etiological treatment of COVID-19 is still lacking; COVID-19 also causes damages to various organs that affects therapeutics and mortality of the patients. Surveillance of the treatment responses and organ injury assessment of COVID-19 patients are of high clinical value. In this study, we investigated the characteristic fragmentation patterns and explored the potential in tissue injury assessment of plasma cell-free DNA in COVID-19 patients. Through recruitment of 37 COVID-19 patients, 32 controls and analysis of 208 blood samples upon diagnosis and during treatment, we report gross abnormalities in cfDNA of COVID-19 patients, including elevated GC content, altered molecule size and end motif patterns. More importantly, such cfDNA fragmentation characteristics reflect patient-specific physiological changes during treatment. Further analysis on cfDNA tissue-of-origin tracing reveals frequent tissue injuries in COVID-19 patients, which is supported by clinical diagnoses. Hence, our work demonstrates and extends the translational merit of cfDNA fragmentation pattern as valuable analyte for effective treatment monitoring, as well as tissue injury assessment in COVID-19.

Combined Effects of Polydopamine-Assisted Copper Immobilization on 3D-Printed Porous Ti6Al4V Scaffold for Angiogenic and Osteogenic Bone Regeneration.

Numerous studies have demonstrated that biological compounds and trace elements such as dopamine (DA) and copper ions (Cu) could be modified onto the surfaces of scaffolds using a one-step immersion process which is simple, inexpensive and, most importantly, non-cytotoxic. The development and emergence of 3D printing technologies such as selective laser melting (SLM) have also made it possible for us to fabricate bone scaffolds with precise structural designs using metallic compounds. In this study, we fabricated porous titanium scaffolds (Ti) using SLM and modified the surface of Ti with polydopamine (PDA) and Cu. There are currently no other reported studies with such a combination for osteogenic and angiogenic-related applications. Results showed that such modifications did not affect general appearances and microstructural characteristics of the porous Ti scaffolds. This one-step immersion modification allowed us to modify the surfaces of Ti with different concentrations of Cu ions, thus allowing us to fabricate individualized scaffolds for different clinical scenarios. The modification improved the hydrophilicity and surface roughness of the scaffolds, which in turn led to promote cell behaviors of Wharton's jelly mesenchymal stem cells. Ti itself has high mechanical strength, therefore making it suitable for surgical handling and clinical applications. Furthermore, the scaffolds were able to release ions in a sustained manner which led to an upregulation of osteogenic-related proteins (bone alkaline phosphatase, bone sialoprotein and osteocalcin) and angiogenic-related proteins (vascular endothelial growth factor and angiopoietin-1). By combining additive manufacturing, Ti6Al4V scaffolds, surface modification and Cu ions, the novel hybrid 3D-printed porous scaffold could be fabricated with ease and specifically benefited future bone regeneration in the clinic.

Plasma cell-free RNA characteristics in COVID-19 patients.

The pathogenesis of COVID-19 is still elusive, which impedes disease progression prediction, differential diagnosis, and targeted therapy. Plasma cell-free RNAs (cfRNAs) carry unique information from human tissue and thus could point to resourceful solutions for pathogenesis and host-pathogen interactions. Here, we performed a comparative analysis of cfRNA profiles between COVID-19 patients and healthy donors using serial plasma. Analyses of the cfRNA landscape, potential gene regulatory mechanisms, dynamic changes in tRNA pools upon infection, and microbial communities were performed. A total of 380 cfRNA molecules were up-regulated in all COVID-19 patients, of which seven could serve as potential biomarkers (AUC > 0.85) with great sensitivity and specificity. Antiviral (NFKB1A, IFITM3, and IFI27) and neutrophil activation (S100A8, CD68, and CD63)-related genes exhibited decreased expression levels during treatment in COVID-19 patients, which is in accordance with the dynamically enhanced inflammatory response in COVID-19 patients. Noncoding RNAs, including some microRNAs (let 7 family) and long noncoding RNAs (GJA9-MYCBP) targeting interleukin (IL6/IL6R), were differentially expressed between COVID-19 patients and healthy donors, which accounts for the potential core mechanism of cytokine storm syndromes; the tRNA pools change significantly between the COVID-19 and healthy group, leading to the accumulation of SARS-CoV-2 biased codons, which facilitate SARS-CoV-2 replication. Finally, several pneumonia-related microorganisms were detected in the plasma of COVID-19 patients, raising the possibility of simultaneously monitoring immune response regulation and microbial communities using cfRNA analysis. This study fills the knowledge gap in the plasma cfRNA landscape of COVID-19 patients and offers insight into the potential mechanisms of cfRNAs to explain COVID-19 pathogenesis.

The effects of a 3D-printed magnesium-/strontium-doped calcium silicate scaffold on regulation of bone regeneration via dual-stimulation of the AKT and WNT signaling pathways.

Numerous studies have demonstrated that calcium silicate (CS) can be doped with various trace metal elements such as strontium (Sr) or magnesium (Mg). These studies have confirmed that such modifications promote bone regeneration. However, the development and emergence of 3D printing have further made it possible to fabricate bone grafts with precise structural designs using multi-bioceramics so as to better suit specific clinical requirements. We fabricated scaffolds using Mg-doped CS as the outer layer with Sr-doped CS in the center. In addition, PCL was used to improve printability of the scaffolds. This enhanced Mg and Sr architecture prevented premature degradation of the scaffolds during immersion while enabling the release of ions in a sustained manner in order to achieve the desired therapeutic goals. Even the capabilities of stem cells were shown to be enhanced when cultured on these scaffolds. Furthermore, the hybrid scaffolds were found to up-regulate the expression of bone-related proteins such as factors leading to differentiation-inducing pathways, including PI3K/Akt, Wnt, and TRPM7. The in vivo performance of the proposed scaffolds was assessed using micro-CT. The histological results revealed that the hybrid scaffolds were able to further enhance bone regeneration as compared to uni-bioceramics. By combining 3D printing, multi-ceramics, and trace metal elements, a novel hybrid scaffold could be fabricated with ease and specifically suited to future bone tissue engineering applications.

Additive Manufacturing of Caffeic Acid-Inspired Mineral Trioxide Aggregate/Poly-ε-Caprolactone Scaffold for Regulating Vascular Induction and Osteogenic Regeneration of Dental Pulp Stem Cells.

Mineral trioxide aggregate (MTA) is a common biomaterial used in endodontics regeneration due to its antibacterial properties, good biocompatibility and high bioactivity. Surface modification technology allows us to endow biomaterials with the necessary biological targets for activation of specific downstream functions such as promoting angiogenesis and osteogenesis. In this study, we used caffeic acid (CA)-coated MTA/polycaprolactone (PCL) composites and fabricated 3D scaffolds to evaluate the influence on the physicochemical and biological aspects of CA-coated MTA scaffolds. As seen from the results, modification of CA does not change the original structural characteristics of MTA, thus allowing us to retain the properties of MTA. CA-coated MTA scaffolds were shown to have 25% to 55% higher results than bare scaffold. In addition, CA-coated MTA scaffolds were able to significantly adsorb more vascular endothelial growth factors (p < 0.05) secreted from human dental pulp stem cells (hDPSCs). More importantly, CA-coated MTA scaffolds not only promoted the adhesion and proliferation behaviors of hDPSCs, but also enhanced angiogenesis and osteogenesis. Finally, CA-coated MTA scaffolds led to enhanced subsequent in vivo bone regeneration of the femur of rabbits, which was confirmed using micro-computed tomography and histological staining. Taken together, CA can be used as a potently functional bioactive coating for various scaffolds in bone tissue engineering and other biomedical applications in the future.