Scaffold-based tissue engineering strategies for soft-hard interface regeneration

Evaluation of the effects of cartilage decellularized ECM in optimizing PHB-chitosan-HNT/chitosan-ECM core-shell electrospun scaffold: Physicochemical and biological properties

Cartilage regeneration is still a highly challenging field due to its low self-healing ability. This study used a core-shell electrospinning technique to enhance cartilage tissue engineering by incorporating cartilage extracellular matrix (ECM). The core of fibers included poly(3-hydroxybutyrate)-Chitosan (PHB-Cs) and Halloysite nanotubes. The shell of fibers consisted of Cs and ECM (0, 1, 3, 5 wt%). Subsequently, the scaffolds were named 0E, 1E, 3E, and 5E. The study aimed to assess the impact of ECM on cellular behavior and chondrogenesis. Our findings indicate that ECM reduced fiber diameter from 775 nm for the 0E scaffold to 454 nm for the 1E scaffold. Water contact angle measurements revealed an increasing trend by ECM addition, from 42° for 0E to 67° for 1E. According to mechanical analysis, the 1E scaffold represented the highest strength (5.81 MPa) and strain (3.17%). Based on these analyses, the 1E was considered the optimum scaffold. MTT analysis showed cell viability of over 80% for the 0E and 1E. Also, the gene expression level was assessed for Collagen II, Aggrecan, SOX 9, and Collagen X. The results represented that in the 1E scaffold Collagen II, Aggrecan, and SOX 9 were more upregulated at the end of the 21st day. However, in the 1E scaffold collagen X, as a hypertrophy marker, was downregulated at the end of the experiment. Overall, these results confirmed the potential of the 1E scaffold to be introduced as a promising cartilage tissue engineering scaffold for further studies.

Engineered Osteochondral Scaffolds with Bioactive Cartilage Zone for Enhanced Articular Cartilage Regeneration

Despite progress, osteochondral (OC) tissue engineering strategies face limitations in terms of articular cartilage layer development and its integration with the underlying bone tissue. The main objective of this study is to develop a zonal OC scaffold with native biochemical signaling in the cartilage zone to promote articular cartilage development devoid of cells and growth factors. Herein, we report the development and in vivo assessment of a novel gradient and zonal-structured scaffold for OC defect regeneration. The scaffold system is composed of a mechanically supportive 3D-printed template containing decellularized cartilage extracellular matrix (ECM) biomaterial in the cartilage zone that possesses bioactive characteristics, such as chemotactic activity and native tissue biochemical composition. OC scaffolds with a bioactive cartilage zone were implanted in vivo in a rabbit osteochondral defect model and assessed for gross morphology, matrix deposition, cellular distribution, and overall tissue regeneration. The scaffold system supported recruitment and infiltration of host cells into the cartilage zone of the graft, which led to increased ECM deposition and physiologically relevant articular cartilage tissue formation. Semi-quantitative ICRS scoring (overall score double for OC scaffold with bioactive cartilage zone compared to PLA scaffold) further confirm the bioactive scaffold enhanced articular cartilage engineering. This strategy of designing bioactive scaffolds to promote endogenous cellular infiltration can be a much simpler and effective approach for OC tissue repair and regeneration.

Treatment of Denervated Muscle Atrophy by Injectable Dual-Responsive Hydrogels Loaded with Extracellular Vesicles

Denervated muscle atrophy, a common outcome of nerve injury, often results in irreversible fibrosis due to the limited effectiveness of current therapeutic interventions. While extracellular vesicles (EVs) offer promise for treating muscle atrophy, their therapeutic potential is hindered by challenges in delivery and bioactivity within the complex microenvironment of the injury site. To address this issue, an injectable hydrogel is developed that is responsive to both ultrasound and pH, with inherent anti-inflammatory and antioxidant properties, designed to improve the targeted delivery of stem cell-derived EVs. This hydrogel system allows for controlled release of EVs from human umbilical cord mesenchymal stem cells (HUC-MSCs), adapting to the specific conditions of the injury environment. In vivo studies using a rat model of nerve injury demonstrated that the EV-loaded hydrogel (EVs@UR-gel) significantly preserved muscle function. Six weeks post-nerve reconstruction, treated rats exhibited muscle strength, circumference, and wet weight reaching 89.53 ± 0.96%, 76.02 ± 7.49%, and 88.0 ± 2.65% of healthy controls, respectively, alongside an improvement in the sciatic nerve index (-0.11 ± 0.09). This platform presents a novel therapeutic approach by maintaining EV bioactivity, enabling tunable release based on the disease state, and facilitating the restoration of muscle structure and function.

Engineering soft-hard tissue interfaces in dental and craniofacial system by spatially controlled bioactivities

The interface between soft and hard tissues is constituted by a gradient change of cell types and matrix compositions that are optimally designed for proper load transmission and injury protection. In the musculoskeletal system, the soft-hard tissue interfaces at tendon-bone, ligament-bone, and meniscus-bone have been extensively researched as regenerative targets. Similarly, extensive research efforts have been made to guide the regeneration of multi-tissue complexes in periodontium. However, the other soft-hard tissue interfaces in the dental and craniofacial system have been somewhat neglected. This review discusses the clinical significance of developing regenerative strategies for soft-hard tissue interfaces in the dental and craniofacial system. It also discusses the research progress in the field focused on bioengineering approaches using 3D scaffolds equipped with spatially controlled bioactivities. The remaining challenges, future perspectives, and considerations for the clinical translation of bioactive scaffolds are also discussed.

Regenerative properties of bone marrow mesenchymal stem cell derived exosomes in rotator cuff tears

ABSTRCT

Rotator cuff injury (RCI), characterized by shoulder pain and restricted mobility, represents a subset of tendon-bone insertion injuries (TBI). In the majority of cases, surgical reconstruction of the affected tendons or ligaments is required to address the damage. However, numerous clinical failures have underscored the suboptimal outcomes associated with such procedures. Further investigations have revealed that these failures are largely attributable to delayed healing at the tendon-bone interface, excessive formation of vascularized scar tissue, and inadequate integration of tendon grafts within bone tunnels. As a result, the healing process of rotator cuff injuries faces significant challenges.Bone marrow-derived mesenchymal stem cell exosomes (BMSC-exos) have emerged as a prominent focus of research within the field of bioengineering, owing to their remarkable potential to regulate cellular proliferation and differentiation, modulate immune responses, and facilitate tissue repair and regeneration following cellular damage. In this review, we explore the anti-inflammatory, angiogenic, anti-scarring, and bone metabolism-modulating effects of BMSC-exos in the context of rotator cuff injury. Additionally, we address the limitations and ongoing challenges within current research, offering insights that could guide the clinical application of BMSC-exos in the treatment of rotator cuff injuries in the future.

Surface modification strategies to reinforce the soft tissue seal at transmucosal region of dental implants

Soft tissue seal around the transmucosal region of dental implants is crucial for shielding oral bacterial invasion and guaranteeing the long-term functioning of implants. Compared with the robust periodontal tissue barrier around a natural tooth, the peri-implant mucosa presents a lower bonding efficiency to the transmucosal region of dental implants, due to physiological structural differences. As such, the weaker soft tissue seal around the transmucosal region can be easily broken by oral pathogens, which may stimulate serious inflammatory responses and lead to the development of peri-implant mucositis. Without timely treatment, the curable peri-implant mucositis would evolve into irreversible peri-implantitis, finally causing the failure of implantation. Herein, this review has summarized current surface modification strategies for the transmucosal region of dental implants with improved soft tissue bonding capacities (e.g., improving surface wettability, fabricating micro/nano topographies, altering the surface chemical composition and constructing bioactive coatings). Furthermore, the surfaces with advanced soft tissue bonding abilities can be incorporated with antibacterial properties to prevent infections, and/or with immunomodulatory designs to facilitate the establishment of soft tissue seal. Finally, we proposed future research orientations for developing multifunctional surfaces, thus establishing a firm soft tissue seal at the transmucosal region and achieving the long-term predictability of dental implants.

Tissue-engineered collagen matrix loaded with rat adipose-derived stem cells/human amniotic mesenchymal stem cells for rotator cuff tendon-bone repair

The rotator cuff tendon-bone interface tissue exhibits high heterogeneity in its composition and structure, with collagen being its primary component. Here, we prepared tissue-engineered decellularized live hyaline cartilage grafts (dLHCG), this dLHCG scaffold's bioactive ECM mainly consists of collagen II, proteoglycans, and fibronectin, presenting a cartilage-like lacuna microstructure. The dLHCG scaffold loaded human amniotic mesenchymal stem cells (hAMSCs) and adipose stem cells (ADSCs) were implanted into the interface. The dLHCG scaffold could maintain the pluripotency of stem cells, supporting the proliferation, osteogenic differentiation, and tenogenic differentiation of the MSCs. The collagen II, through the integrin α2β1-FAK-JNK signaling axis, promotes Runx-2 activation, playing a better regulatory role in the early osteogenic differentiation of MSCs, enhancing bone defect repair through an endochondral ossification process. The in vivo rat model demonstrated that 12 weeks post-operation, the MSC-loaded dLHCG scaffold group exhibited continuous aligned collagen fibers at the tendon-bone interface, with significantly enhanced biomechanical function compared to the control group. The dLHCG scaffold create an efficient interface, which promoting the restoration of the soft-hard gradient structure tissue at the junction between the scaffold and the host tissue, thereby providing a rational and promising strategy for the rapid healing of the rotator cuff injury.

Cross-linking manipulation of waterborne biodegradable polyurethane for constructing mechanically adaptable tissue engineering scaffolds

Mechanical adaptation of tissue engineering scaffolds is critically important since natural tissue regeneration is highly regulated by mechanical signals. Herein, we report a facile and convenient strategy to tune the modulus of waterborne biodegradable polyurethanes (WBPU) via cross-linking manipulation of phase separation and water infiltration for constructing mechanically adaptable tissue engineering scaffolds. Amorphous aliphatic polycarbonate and trifunctional trimethylolpropane were introduced to polycaprolactone-based WBPUs to interrupt interchain hydrogen bonds in the polymer segments and suppress microphase separation, inhibiting the crystallization process and enhancing covalent cross-linking. Intriguingly, as the crosslinking density of WBPU increases and the extent of microphase separation decreases, the material exhibits a surprisingly soft modulus and enhanced water infiltration. Based on this strategy, we constructed WBPU scaffolds with a tunable modulus to adapt various cells for tissue regeneration and regulate the immune response. As a representative application of brain tissue regeneration model in vivo, it was demonstrated that the mechanically adaptable WBPU scaffolds can guide the migration and differentiation of endogenous neural progenitor cells into mature neurons and neuronal neurites and regulate immunostimulation with low inflammation. Therefore, the proposed strategy of tuning the modulus of WBPU can inspire the development of novel mechanically adaptable biomaterials, which has very broad application value.

Achieving tendon enthesis regeneration across length scales

Surgical reattachment of tendon to bone is a clinical challenge, with unacceptably high retear rates in the early period after repair. A primary reason for these repeated tears is that the multiscale toughening mechanisms found at the healthy tendon enthesis are not regenerated during tendon-to-bone healing. The need for technologies to improve these outcomes is pressing, and the tissue engineering community has responded with many advances that hold promise for eventually regenerating the multiscale tissue interface that transfers loads between the two dissimilar materials, tendon, and bone. This review provides an assessment of the state of these approaches, with the aim of identifying a critical agenda for future progress.

Comparative effect of skeletal stem cells versus bone marrow mesenchymal stem cells on rotator cuff tendon-bone healing

BACKGROUND

Bone marrow mesenchymal stem cells (BMSCs) have immense potential in applications for the enhancement of tendon-bone (T-B) healing. Recently, it has been well-reported that skeletal stem cells (SSCs) could induce bone and cartilage regeneration. Therefore, SSCs represent a promising choice for cell-based therapies to improve T-B healing. In this study, we aimed to compare the therapeutic potential of SSCs and BMSCs for tendon-bone healing.

METHODS

SSCs and BMSCs were isolated by flow cytometry, and their proliferation ability was measured by CCK-8 assay. The osteogenic, chondrogenic, and adipogenic gene expression in cells was detected by quantitative real-time polymerase chain reaction (qRT-PCR). C57BL/6 mice underwent unilateral supraspinatus tendon detachment and repair, and the mice were then randomly allocated to 4 groups: control group (tendon-bone interface without any treatment), hydrogel group (administration of blank hydrogel into the tendon-bone interface), hydrogel + BMSCs group (administration of hydrogel with BMSCs into the tendon-bone interface), and hydrogel + SSCs group (administration of hydrogel with SSCs into the tendon-bone interface). Histological staining, Micro-computed tomography (Micro-CT) scanning, biomechanical testing, and qRT-PCR were performed to assay T-B healing at 4 and 8 weeks after surgery.

RESULTS

SSCs showed more cell proportion, exhibited stronger multiplication capacity, and expressed higher osteogenic and chondrogenic markers and lower adipogenic markers than BMSCs. In vivo assay, the SSCs group showed a better-maturated interface which was characterized by richer chondrocytes and more proteoglycan deposition, as well as more newly formed bone at the healing site and increased mechanical properties when compared to other there groups. qRT-PCR analysis revealed that the healing interface in the SSCs group expressed more transcription factors essential for osteogenesis and chondrogenesis than the interfaces in the other groups.

CONCLUSIONS

Overall, the results demonstrated the superior therapeutic potential of SSCs over BMSCs in tendon-bone healing.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This current study provides valuable insights that SSCs may be a more effective cell therapy for enhancing T-B healing compared to BMSCs.

3D printing materials and 3D printed surgical devices in oral and maxillofacial surgery: design, workflow and effectiveness

Oral and maxillofacial surgery is a specialized surgical field devoted to diagnosing and managing conditions affecting the oral cavity, jaws, face and related structures. In recent years, the integration of 3D printing technology has revolutionized this field, offering a range of innovative surgical devices such as patient-specific implants, surgical guides, splints, bone models and regenerative scaffolds. In this comprehensive review, we primarily focus on examining the utility of 3D-printed surgical devices in the context of oral and maxillofacial surgery and evaluating their efficiency. Initially, we provide an insightful overview of commonly utilized 3D-printed surgical devices, discussing their innovations and clinical applications. Recognizing the pivotal role of materials, we give consideration to suitable biomaterials and printing technology of each device, while also introducing the emerging fields of regenerative scaffolds and bioprinting. Furthermore, we delve into the transformative impact of 3D-printed surgical devices within specific subdivisions of oral and maxillofacial surgery, placing particular emphasis on their rejuvenating effects in bone reconstruction, orthognathic surgery, temporomandibular joint treatment and other applications. Additionally, we elucidate how the integration of 3D printing technology has reshaped clinical workflows and influenced treatment outcomes in oral and maxillofacial surgery, providing updates on advancements in ensuring accuracy and cost-effectiveness in 3D printing-based procedures.

Reprogramming tendon healing: a guide to novel molecular tools

Tendons are a frequent site of injury, which greatly impairs the movement and locomotion of patients. Regrettably, injuries at the tendon frequently require surgical intervention, which leads to a long path to recovery. Moreover, the healing of tendons often involves the formation of scar tissue at the site of injury with poor mechanical properties and prone to re-injury. Tissue engineering carries the promise of better and more effective solutions to the improper healing of tendons. Lately, the field of regenerative medicine has seen a significant increase in the focus on the potential use of non-coding RNAs (e.g., siRNAs, miRNAs, and lncRNAs) as molecular tools for tendon tissue engineering. This class of molecules is being investigated due to their ability to act as epigenetic regulators of gene expression and protein production. Thus, providing a molecular instrument to fine-tune, reprogram, and modulate the processes of tendon differentiation, healing, and regeneration. This review focuses particularly on the latest advances involving the use of siRNAs, miRNAs, and lncRNAs in tendon tissue engineering applications.

Multifunctional MXene-Based Platforms for Soft and Bone Tissue Regeneration and Engineering

MXenes and their composites hold great promise in the field of soft and bone tissue regeneration and engineering (TRE). However, there are challenges that need to be overcome, such as ensuring biocompatibility and controlling the morphologies of MXene-based scaffolds. The future prospects of MXenes in TRE include enhancing biocompatibility through surface modifications, developing multifunctional constructs, and conducting in vivo studies for clinical translation. The purpose of this perspective about MXenes and their composites in soft and bone TRE is to critically evaluate their potential applications and contributions in this field. This perspective aims to provide a comprehensive analysis of the challenges, advantages, limitations, and future prospects associated with the use of MXenes and their composites for soft and bone TRE. By examining the existing literature and research, the review seeks to consolidate the current knowledge and highlight the key findings and advancements in MXene-based TRE. It aims to contribute to the understanding of MXenes' role in promoting soft and bone TRE, addressing the challenges faced in terms of biocompatibility, morphology control, and tissue interactions.

Cancer cell response to extrinsic and intrinsic mechanical cue: opportunities for tumor apoptosis strategies

Increasing studies have revealed the importance of mechanical cues in tumor progression, invasiveness and drug resistance. During malignant transformation, changes manifest in either the mechanical properties of the tissue or the cellular ability to sense and respond to mechanical signals. The major focus of the review is the subtle correlation between mechanical cues and apoptosis in tumor cells from a mechanobiology perspective. To begin, we focus on the intracellular force, examining the mechanical properties of the cell interior, and outlining the role that the cytoskeleton and intracellular organelle-mediated intracellular forces play in tumor cell apoptosis. This article also elucidates the mechanisms by which extracellular forces guide tumor cell mechanosensing, ultimately triggering the activation of the mechanotransduction pathway and impacting tumor cell apoptosis. Finally, a comprehensive examination of the present status of the design and development of anti-cancer materials targeting mechanotransduction is presented, emphasizing the underlying design principles. Furthermore, the article underscores the need to address several unresolved inquiries to enhance our comprehension of cancer therapeutics that target mechanotransduction.

3D printing sequentially strengthening high-strength natural polymer hydrogel bilayer scaffold for cornea regeneration

3D printing of high-strength natural polymer biodegradable hydrogel scaffolds simultaneously resembling the biomechanics of corneal tissue and facilitating tissue regeneration remains a huge challenge due to the inherent brittleness of natural polymer hydrogels and the demanding requirements of printing. Herein, concentrated aqueous solutions of gelatin and carbohydrazide-modified alginate (Gel/Alg-CDH) are blended to form a natural polymer hydrogel ink, where the hydrazides in Alg-CDH are found to form strong hydrogen bonds with the gelatin. The hydrogen-bonding-strengthened Gel/Alg-CDH hydrogel demonstrates an appropriate thickened viscosity and shear thinning for extrusion printing. The strong hydrogen bonds contribute to remarkably increased mechanical properties of Gel/Alg-CDH hydrogel with a maximum elongation of over 400%. In addition, sequentially Ca2+-physical crosslinking and then moderately chemical crosslinking significantly enhance the mechanical properties of Gel/Alg-CDH hydrogels that ultimately exhibit an intriguing J-shaped stress-strain curve (tensile strength of 1.068 MPa and the toughness of 677.6 kJ/m2). The dually crosslinked Gel-Alg-CDH-Ca2+-EDC hydrogels demonstrate a high transparency, physiological swelling stability and rapid enzymatic degradability, as well as suturability. The growth factor and drug-loaded biomimetic bilayer hydrogel scaffold are customized via a multi-nozzle printing system. This bioactive bilayer hydrogel scaffold considerably promotes regeneration of corneal epithelium and stroma and inhibits cornea scarring in rabbit cornea keratoplasty.

Recent advances and perspectives on natural latex serum and its fractions for biomedical applications

Advances and the discovery of new biomaterials have opened new frontiers in regenerative medicine. These biomaterials play a key role in current medicine by improving the life quality or even saving the lives of millions of people. Since the 2000s, Natural Rubber Latex (NRL) has been employed as wound dressings, mechanical barrier for Guided Bone Regeneration (GBR), matrix for drug delivery, and grafting. NRL is a natural polymer that can stimulate cell proliferation, neoangiogenesis, and extracellular matrix (ECM) formation. Furthermore, it is well established that proteins and other biologically active molecules present in the Natural Latex Serum (NLS) are responsible for the biological properties of NRL. NLS can be obtained from NRL by three main methods, namely (i) Centrifugation (fractionation of NRL in distinct fractions), (ii) Coagulation and sedimentation (coagulating NRL to separate the NLS from rubber particles), and (iii) Alternative extraction process (elution from NRL membrane). In this review, the chemical composition, physicochemical properties, toxicity, and other biological information such as osteogenesis, vasculogenesis, adhesion, proliferation, antimicrobial behavior, and antitumoral activity of NLS, as well as some of its medical instruments and devices are discussed. The progress in NLS applications in the biomedical field, more specifically in cell cultures, alternative animals, regular animals, and clinical trials are also discussed. An overview of the challenges and future directions of the applications of NLS and its derivatives in tissue engineering for hard and soft tissue regeneration is also given.

A construct of adipose-derived mesenchymal stem cells-laden collagen scaffold for fertility restoration by inhibiting fibrosis in a rat model of endometrial injury

Severe endometrium damage causes pathological conditions such as thin endometrium and intrauterine adhesion, resulting in uterine factor infertility. Mesenchymal stem cell (MSC) therapy is a promising strategy in endometrial repair; yet, exogenous MSCs still raise concerns for safety and ethical issues. Human adipose-derived mesenchymal stem cells (ADMSCs) residing in adipose tissue have high translational potentials due to their autologous origin. To harness the high translation potentials of ADMSC in clinical endometrium regeneration, here we constructed an ADMSCs composited porous scaffold (CS/ADMSC) and evaluated its effectiveness on endometrial regeneration in a rat endometrium-injury model. We found that CS/ADMSC intrauterine implantation (i) promoted endometrial thickness and gland number, (ii) enhanced tissue angiogenesis, (iii) reduced fibrosis and (iv) restored fertility. We ascertained the pro-proliferation, pro-angiogenesis, immunomodulating and anti-fibrotic effects of CS/ADMSC in vitro and revealed that the CS/ADMSC influenced extracellular matrix composition and organization by a transcriptomic analysis. Our results demonstrated the effectiveness of CS/ADMSC for endometrial regeneration and provided solid proof for our future clinical study.

Incorporation of kartogenin and silk fibroin scaffolds promotes rat articular cartilage regeneration through enhancement of antioxidant functions

Treating articular cartilage defects in patients remains a challenging task due to the absence of blood vessels within the cartilage tissue. The regenerative potential is further compromised by an imbalance between anabolism and catabolism, induced by elevated levels of reactive oxygen species. However, the advent of tissue engineering introduces a promising strategy for cartilage regeneration, offering viable solutions such as mechanical support and controlled release of chondrogenic molecules or cytokines. In this study, we developed an antioxidant scaffold by incorporating natural silk fibroin (SF) and kartogenin (KGN)-loaded liposomes (SF-Lipo@KGN). The scaffold demonstrated appropriate pore size, connectivity, and water absorption and the sustained release of KGN was achieved through the encapsulation of liposomes. In vitro experiments revealed that the SF-Lipo@KGN scaffolds exhibited excellent biocompatibility, as evidenced by enhanced cell adhesion, migration, and proliferation of chondrocytes. The SF-Lipo@KGN scaffolds were found to stimulate cartilage matrix synthesis through the activation of the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 antioxidant signaling pathway. In vivo experiments demonstrated the effective promotion of articular cartilage regeneration by the SF-Lipo@KGN scaffolds, which enhanced extracellular matrix anabolism and restored the intrinsic redox homeostasis. Overall, this study successfully developed biomimetic KGN-loaded scaffolds that restore cartilage redox homeostasis, indicating promising prospects for cartilage tissue engineering.

Sequential intervention of anti-inflammatory and osteogenesis with silk fibroin coated polyethylene terephthalate artificial ligaments for anterior cruciate ligament reconstruction

Graft-host integration after the anterior cruciate ligament (ACL) reconstruction sequentially follows the prognosis from the inflammation period to the regeneration period. However, due to insufficient bioactivity, polyethylene terephthalate (PET) artificial ligaments often require a long period for graft-host integration. To improve graft-host integration, sequential therapy targeting multifactor is widely advocated. In this study, a multilayer regenerated silk fibroin (RSF) coating loaded with heparin and bone morphogenetic protein binding peptide (BBP) for differentiated release was introduced on the surface of the PET artificial ligament by a stepwise deposition method. The drug release profiles of heparin and BBP on the coated PET artificial ligament indicated the features of differential drug release, i.e., with heparin in the outermost layer releasing a significant amount (more than 60%) during the first 5 days while BBP in the inner layer only releasing a small amount (ca. 30%) within 1 week without burst release. Based on the isometric ACL reconstruction model of rabbits, such drug-loaded RSF coating was verified to be able to modulate the early inflammatory response and promote the maturation of the graft in the articular cavity, meanwhile, it provided a continuous and stable signal of osteogenic induction to improve graft-bone integration. Thus, sequential intervention with heparin and BBP proved to be a reliable combination, and multifunctional RSF-coated PET artificial ligaments hold great potential for improving the clinical efficacy of ACL reconstruction.

Fabrication of Injectable Kartogenin-Conjugated Composite Hydrogel with a Sustained Drug Release for Cartilage Repair

Cartilage tissue engineering has attracted great attention in defect repair and regeneration. The utilization of bioactive scaffolds to effectively regulate the phenotype and proliferation of chondrocytes has become an elemental means for cartilage tissue regeneration. On account of the simultaneous requirement of mechanical and biological performances for tissue-engineered scaffolds, in this work we prepared a naturally derived hydrogel composed of a bioactive kartogenin (KGN)-linked chitosan (CS-KGN) and an aldehyde-modified oxidized alginate (OSA) via the highly efficient Schiff base reaction and multifarious physical interactions in mild conditions. On the basis of the rigid backbones and excellent biocompatibility of these two natural polysaccharides, the composite hydrogel demonstrated favorable morphology, easy injectability, good mechanical strength and tissue adhesiveness, low swelling ratio, long-term sustainable KGN release, and facilitated bone marrow mesenchymal stem cell activity, which could simultaneously provide the mechanical and biological supports to promote chondrogenic differentiation and repair the articular cartilage defects. Therefore, we believe this work can offer a designable consideration and potential alternative candidate for cartilage and other soft tissue implants.

Enhancement of Antibacterial Properties, Surface Morphology and In Vitro Bioactivity of Hydroxyapatite-Zinc Oxide Nanocomposite Coating by Electrophoretic Deposition Technique

To develop medical-grade stainless-steel 316L implants that are biocompatible, non-toxic and antibacterial, such implants need to be coated with biomaterials to meet the current demanding properties of biomedical materials. Hydroxyapatite (HA) is commonly used as a bone implant coating due to its excellent biocompatible properties. Zinc oxide (ZnO) nanoparticles are added to HA to increase its antibacterial and cohesion properties. The specimens were made of a stainless-steel grade 316 substrate coated with HA-ZnO using the electrophoretic deposition technique (EPD), and were subsequently characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), stylus profilometry, electrochemical corrosion testing and Fourier transform infrared (FTIR) spectroscopy. Additionally, cross-hatch tests, cell viability assays, antibacterial assessment and in vitro activity tests in simulated body fluid (SBF) were performed. The results showed that the HA-ZnO coating was uniform and resistant to corrosion in an acceptable range. FTIR confirmed the presence of HA-ZnO compositions, and the in vitro response and adhesion were in accordance with standard requirements for biomedical materials. Cell viability confirmed the viability of cells in an acceptable range (>70%). In addition, the antibacterial activity of ZnO was confirmed on Staphylococcus aureus. Thus, the HA-ZnO samples are recommended for biomedical applications.

Recent advances in tendon tissue engineering strategy

Tendon injuries often result in significant pain and disability and impose severe clinical and financial burdens on our society. Despite considerable achievements in the field of regenerative medicine in the past several decades, effective treatments remain a challenge due to the limited natural healing capacity of tendons caused by poor cell density and vascularization. The development of tissue engineering has provided more promising results in regenerating tendon-like tissues with compositional, structural and functional characteristics comparable to those of native tendon tissues. Tissue engineering is the discipline of regenerative medicine that aims to restore the physiological functions of tissues by using a combination of cells and materials, as well as suitable biochemical and physicochemical factors. In this review, following a discussion of tendon structure, injury and healing, we aim to elucidate the current strategies (biomaterials, scaffold fabrication techniques, cells, biological adjuncts, mechanical loading and bioreactors, and the role of macrophage polarization in tendon regeneration), challenges and future directions in the field of tendon tissue engineering.