3D Printed Chondrogenic Functionalized PGS Bioactive Scaffold for Cartilage Regeneration

Mechanically skin-like and water-resistant self-healing bioelastomer for high-tension wound healing

The biomedical application of self-healing materials in wet or (under)water environments is quite challenging because the insulation and dissociation effects of water molecules significantly reduce the reconstruction of material-interface interactions. Rapid closure with uniform tension of high-tension wounds is often difficult, leading to further deterioration and scarring. Herein, a new type of thermosetting water-resistant self-healing bioelastomer (WRSHE) was designed by synergistically incorporating a stable polyglycerol sebacate (PGS) covalent crosslinking network and triple hybrid dynamic networks consisting of reversible disulfide metathesis (SS), and dimethylglyoxime urethane (Dou) and hydrogen bonds. And a resveratrol-loaded WRSHE (Res@WRSHE) was developed by a swelling, absorption, and crosslinked network locking strategy. WRSHEs exhibited skin-like mechanical properties in terms of nonlinear modulus behavior, biomimetic softness, high stretchability, and good elasticity, and they also achieved ultrafast and highly efficient self-healing in various liquid environments. For wound-healing applications of high-tension full-thickness skin defects, the convenient surface assembly by self-healing of WRSHEs provides uniform contraction stress to facilitate tight closure. Moreover, Res@WRSHEs gradually release resveratrol, which helps inflammatory response reduction, promotes blood vessel regeneration, and accelerates wound repair.

Multi-Tissue Integrated Tissue-Engineered Trachea Regeneration Based on 3D Printed Bioelastomer Scaffolds

Functional segmental trachea reconstruction is a critical concern in thoracic surgery, and tissue-engineered trachea (TET) holds promise as a potential solution. However, current TET falls short in fully restoring physiological function due to the lack of the intricate multi-tissue structure found in natural trachea. In this research, a multi-tissue integrated tissue-engineered trachea (MI-TET) is successfully developed by orderly assembling various cells (chondrocytes, fibroblasts and epithelial cells) on 3D-printed PGS bioelastomer scaffolds. The MI-TET closely resembles the complex structures of natural trachea and achieves the integrated regeneration of four essential tracheal components: C-shaped cartilage ring, O-shaped vascularized fiber ring, axial fiber bundle, and airway epithelium. Overall, the MI-TET demonstrates highly similar multi-tissue structures and physiological functions to natural trachea, showing promise for future clinical advancements in functional TETs.

A xenogeneic extracellular matrix-based 3D printing scaffold modified by ceria nanoparticles for craniomaxillofacial hard tissue regeneration via osteo-immunomodulation

Hard tissue engineering scaffolds especially 3D printed scaffolds were considered an excellent strategy for craniomaxillofacial hard tissue regeneration, involving crania and facial bones and teeth. Porcine treated dentin matrix (pTDM) as xenogeneic extracellular matrix has the potential to promote the stem cell differentiation and mineralization as it contains plenty of bioactive factors similar with human-derived dentin tissue. However, its application might be impeded by the foreign body response induced by the damage-associated molecular patterns of pTDM, which would cause strong inflammation and hinder the regeneration. Ceria nanoparticles (CNPs) show a great promise at protecting tissue from oxidative stress and influence the macrophages polarization. Using 3D-bioprinting technology, we fabricated a xenogeneic hard tissue scaffold based on pTDM xenogeneic TDM-polycaprolactone (xTDM/PCL) and we modified the scaffolds by CNPs (xTDM/PCL/CNPs). Through series ofin vitroverification, we found xTDM/PCL/CNPs scaffolds held promise at up-regulating the expression of osteogenesis and odontogenesis related genes including collagen type 1, Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein-2, osteoprotegerin, alkaline phosphatase (ALP) and DMP1 and inducing macrophages to polarize to M2 phenotype. Regeneration of bone tissues was further evaluated in rats by conducting the models of mandibular and skull bone defects. Thein vivoevaluation showed that xTDM/PCL/CNPs scaffolds could promote the bone tissue regeneration by up-regulating the expression of osteogenic genes involving ALP, RUNX2 and bone sialoprotein 2 and macrophage polarization into M2. Regeneration of teeth evaluated on beagles demonstrated that xTDM/PCL/CNPs scaffolds expedited the calcification inside the scaffolds and helped form periodontal ligament-like tissues surrounding the scaffolds.

Electrospun Composite PLLA-PPSB Nanofiber Nerve Conduits for Peripheral Nerve Defects Repair and Regeneration

Peripheral nerve injury (PNI) is a common clinical problem and regenerating peripheral nerve defects remain a significant challenge. Poly(polyol sebacate) (PPS) polymers are developed as promising materials for biomedical applications due to their biodegradability, biocompatibility, elastomeric properties, and ease of production. However, the application of PPS-based biomaterials in nerve tissue engineering, especially in PNI repair, is limited. In this study, PPS-based composite nanofibers poly(l-lactic acid)-poly(polycaprolactone triol-co-sebacic acid-co-N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt) (PLLA-PPSB) are aimed to construct through electrospinning and assess their in vitro biocompatibility with Schwann cells (SCs) and in vivo repair capabilities for peripheral nerve defects. For the first time, the biocompatibility and bioactivity of PPS-based nanomaterial are examined at the molecular, cellular, and animal levels for PNI repair. Electrospun PLLA-PPSB nanofibers display favorable physicochemical properties and biocompatibility, providing an effective interface for the proliferation, glial expression, and adhesion of SCs in vitro. In vivo experiments using a 10-mm rat sciatic nerve defect model show that PLLA-PPSB nanofiber nerve conduits enhance myelin formation, axonal regeneration, angiogenesis, and functional recovery. Transcriptome analysis and biological validation indicate that PLLA-PPSB nanofibers may promote SC proliferation by activating the PI3K/Akt signaling pathway. This suggests the promising potential of PLLA-PPSB nanomaterial for PNI repair.

Recent Progress in Advanced Polyester Elastomers for Tissue Engineering and Bioelectronics

Polyester elastomers are highly flexible and elastic materials that have demonstrated considerable potential in various biomedical applications including cardiac, vascular, neural, and bone tissue engineering and bioelectronics. Polyesters are desirable candidates for future commercial implants due to their biocompatibility, biodegradability, tunable mechanical properties, and facile synthesis and fabrication methods. The incorporation of bioactive components further improves the therapeutic effects of polyester elastomers in biomedical applications. In this review, novel structural modification methods that contribute to outstanding mechanical behaviors of polyester elastomers are discussed. Recent advances in the application of polyester elastomers in tissue engineering and bioelectronics are outlined and analyzed. A prospective of the future research and development on polyester elastomers is also provided.