Tri-Layered Doxycycline-, Collagen- and Bupivacaine-Loaded Poly(lactic-co-glycolic acid) Nanofibrous Scaffolds for Tendon Rupture Repair

Inhibiting Friction-Induced Exogenous Adhesion via Robust Lubricative Core-Shell Nanofibers for High-Quality Tendon Repair

Friction is the trigger cause for excessive exogenous adhesion, leading to the poor self-repair of the tendon. To address this problem, we developed electrospun dual-functional nanofibers with surface robust superlubricated performance and bioactive agent delivery to regulate healing balance by reducing exogenous adhesion and promoting endogenous healing. Coaxial electrospinning and our previous developed in situ robust nanocoating growth techniques were employed to create the lubricative/repairable core-shell structured nanofibrous membrane (L/R-NM). The L/R-NM shell featured a robust coating of the zwitterionic PMPC polymer for strong hydration lubrication to resist exogenous healing. The core could achieve sustained platelet-rich plasma release to promote endogenous healing. Friction tests and cell experiments confirmed L/R-NM's prominent lubricating properties and antiadhesive performance in vitro. Rat tendon injury model evaluation indicated that L/R-NM effectively promotes high-quality tendon repair by inhibiting friction-induced exogenous adhesion and promoting endogenous healing. Therefore, we believe that L/R-NM will open a unique novel horizon for tendon repair.

In-vitro and in-vivo assessment of biocompatibility and efficacy of ostrich eggshell membrane combined with platelet-rich plasma in Achilles tendon regeneration

Tendon injuries present significant medical, social, and economic challenges globally. Despite advancements in tendon injury repair techniques, outcomes remain suboptimal due to inferior tissue quality and functionality. Tissue engineering offers a promising avenue for tendon regeneration, with biocompatible scaffolds playing a crucial role. Ostrich eggshell membrane (ESM), characterized by a strong preferential orientation of calcite crystals, forms a semipermeable polymer network with excellent mechanical properties compared to membranes from other bird species, emerging as a potential natural scaffold candidate. Coupled with platelet-rich plasma (PRP), known for its regenerative properties, ESM holds promise for improving tendon repair. This study aims to evaluate the biocompatibility and efficacy of an ESM-PRP scaffold in treating Achilles tendon ruptures, employing in vitro and in vivo assessments to gauge its potential in tendon regeneration in living organisms. Ostrich ESM was prepared from pathogen-free ostrich eggs, sterilized with UV radiation and prepared in desired dimensions before implantation (1.5 × 1 cm). High-resolution scanning electron microscopy (HRSEM) was utilized to visualize the sample morphology and fiber bonding. In vitro biocompatibility was assessed using the MTT assay and DAPI staining, while in vivo biocompatibility was evaluated in a rat model. For the in vivo Achilles tendinopathy assay, rats were divided into groups and subjected to AT rupture followed by treatment with ESM, PRP, or a combination. SEM was employed to evaluate tendon morphology, and real-time PCR was conducted to analyze gene expression levels. The in vivo assay indicated that the ESM scaffold was safe for an extended period of 8 weeks, showing no signs of inflammation based on histopathological analysis. In the Achilles tendon rupture model, combining ESM with PRP enhanced tendon healing after 14 weeks post-surgery. This finding was supported by histopathological, morphological, and mechanical evaluations of tendon tissues compared to normal tendons, untreated tendinopathy, and injured tendons treated with the ESM scaffold. Gene expression analysis revealed significantly increased expression of Col1a1, Col3a1, bFGF, Scleraxis (Scx), and tenomodulin in the ESM-PRP groups. The findings of our study demonstrate that the combination of Ostrich ESM with PRP significantly enhances AT repair and is a biocompatible scaffold for the application in living organisms.

Acute tear versus chronic-degenerated rotator cuff pathologies are associated with divergent tendon metabolite profiles

PURPOSE/AIM

Metabolic disorders are risk factors for rotator cuff injuries, which suggests that the rotator cuff is sensitive to local metabolic fluctuations. However, the link between the metabolic microenvironment and pathologic features of acute tear versus chronic degeneration is currently unknown. The overarching goal of this study was to evaluate alterations in tendon metabolite profiles following acute tear or chronic degeneration of the rotator cuff. We hypothesized that injury types (acute tear vs. chronic degeneration) would result in distinct metabolite profiles relative to clinically unaffected tendon controls.

MATERIALS AND METHODS

We utilized untargeted metabolomics to identify pathways that were altered at the time of rotator cuff repair (RCR; acute tear) or reverse total shoulder arthroplasty (rTSA; chronic degeneration) relative to total shoulder arthroplasty controls (TSA; tendon clinically unaffected).

RESULTS

Acute tears to the rotator cuff were associated with an overall decrease in tendon metabolites. This global decrease was primarily associated with glycolic acid and decreased tricarboxylic acid (TCA) cycle activity. Conversely, chronic tendon specimens from patients undergoing rTSA showed an overall increase in metabolites. Most notably, chronic injury was associated with increased levels of multiple amino acids including alanine, aspartate, lysine, and proline.

CONCLUSIONS

Overall, this study demonstrates that distinct metabolite profiles are associated with injury types, and that therapeutic strategies should address both cellular and matrix components regardless of injury induction. The specific pathways identified paired with validated, established, treatment methods may serve as novel therapeutic targets for patients who suffer from rotator cuff injuries.

Advancements in scaffold for treating ligament injuries; in vitro evaluation

Tendon/ligament (T/L) injuries are a worldwide health problem that affects millions of people annually. Due to the characteristics of tendons, the natural rehabilitation of their injuries is a very complex and lengthy process. Surgical treatment of a T/L injury frequently necessitates using autologous or allogeneic grafts or synthetic materials. Nonetheless, these alternatives have limitations in terms of mechanical properties and histocompatibility, and they do not permit the restoration of the original biological function of the tissue, which can negatively impact the patient's quality of life. It is crucial to find biological materials that possess the necessary properties for the successful surgical treatment of tissues and organs. In recent years, the in vitro regeneration of tissues and organs from stem cells has emerged as a promising approach for preparing autologous tissue and organs, and cell culture scaffolds play a critical role in this process. However, the biological traits and serviceability of different materials used for cell culture scaffolds vary significantly, which can impact the properties of the cultured tissues. Therefore, this review aims to analyze the differences in the biological properties and suitability of various materials based on scaffold characteristics such as cell compatibility, degradability, textile technologies, fiber arrangement, pore size, and porosity. This comprehensive analysis provides valuable insights to aid in the selection of appropriate scaffolds for in vitro tissue and organ culture.

Novel CO2-encapsulated Pluronic F127 hydrogel for the treatment of Achilles tendon injury

Nonsurgical treatment and surgical repairment of injured Achilles tendons seldom restore the wounded tendon to its original elasticity and stiffness. Therefore, we hypothesized that the surgically repaired Achilles tendon can achieve satisfactory regeneration by applying multi-drug encapsulated hydrogels. In this study, a novel bupivacaine-eluting carbon dioxide-encapsulated Pluronic F127 hydrogel (BC-hydrogel) was developed for the treatment of Achilles tendon injuries. The rheological properties of BC-hydrogel were measured. A high-performance liquid chromatography assay was used to assess the release characteristics of bupivacaine in both in vitro and in vivo settings. Furthermore, the effectiveness of BC-hydrogel in treating torn tendons was examined in a rat model, and histological analyses were conducted. Evidently, the degradable hydrogels continuously eluted bupivacaine for more than 14 days. The animal study results revealed that the BC-hydrogel improved the post-surgery mobility of the animals compared with pristine hydrogels. Histological assay results demonstrated a significant reaction to high vascular endothelial growth factor in the surrounding tissues and expression of collagen I within the repaired tendon. This demonstrates the potential of this novel BC-hydrogel as an effective treatment method for Achilles tendon injuries.

Topically Applied Biopolymer-Based Tri-Layered Hierarchically Structured Nanofibrous Scaffold with a Self-Pumping Effect for Accelerated Full-Thickness Wound Healing in a Rat Model

Wound healing has grown to be a significant problem at a global scale. The lack of multifunctionality in most wound dressing-based biopolymers prevents them from meeting all clinical requirements. Therefore, a multifunctional biopolymer-based tri-layered hierarchically nanofibrous scaffold in wound dressing can contribute to skin regeneration. In this study, a multifunctional antibacterial biopolymer-based tri-layered hierarchically nanofibrous scaffold comprising three layers was constructed. The bottom and the top layers contain hydrophilic silk fibroin (SF) and fish skin collagen (COL), respectively, for accelerated healing, interspersed with a middle layer of hydrophobic poly-3-hydroxybutyrate (PHB) containing amoxicillin (AMX) as an antibacterial drug. The advantageous physicochemical properties of the nanofibrous scaffold were estimated by SEM, FTIR, fluid uptake, contact angle, porosity, and mechanical properties. Moreover, the in vitro cytotoxicity and cell healing were assessed by MTT assay and the cell scratching method, respectively, and revealed excellent biocompatibility. The nanofibrous scaffold exhibited significant antimicrobial activity against multiple pathogenic bacteria. Furthermore, the in vivo wound healing and histological studies demonstrated complete wound healing in wounded rats on day 14, along with an increase in the expression level of the transforming growth factor-β1 (TGF-β1) and a decrease in the expression level of interleukin-6 (IL-6). The results revealed that the fabricated nanofibrous scaffold is a potent wound dressing scaffold, and significantly accelerates full-thickness wound healing in a rat model.

Biodegradable Polymer Electrospinning for Tendon Repairment

With the degradation after aging and the destruction of high-intensity exercise, the frequency of tendon injury is also increasing, which will lead to serious pain and disability. Due to the structural specificity of the tendon tissue, the traditional treatment of tendon injury repair has certain limitations. Biodegradable polymer electrospinning technology with good biocompatibility and degradability can effectively repair tendons, and its mechanical properties can be achieved by adjusting the fiber diameter and fiber spacing. Here, this review first briefly introduces the structure and function of the tendon and the repair process after injury. Then, different kinds of biodegradable natural polymers for tendon repair are summarized. Then, the advantages and disadvantages of three-dimensional (3D) electrospun products in tendon repair and regeneration are summarized, as well as the optimization of electrospun fiber scaffolds with different bioactive materials and the latest application in tendon regeneration engineering. Bioactive molecules can optimize the structure of these products and improve their repair performance. Importantly, we discuss the application of the 3D electrospinning scaffold's superior structure in different stages of tendon repair. Meanwhile, the combination of other advanced technologies has greater potential in tendon repair. Finally, the relevant patents of biodegradable electrospun scaffolds for repairing damaged tendons, as well as their clinical applications, problems in current development, and future directions are summarized. In general, the use of biodegradable electrospun fibers for tendon repair is a promising and exciting research field, but further research is needed to fully understand its potential and optimize its application in tissue engineering.

Nanofiber Carriers of Therapeutic Load: Current Trends

The fast advancement in nanotechnology has prompted the improvement of numerous methods for the creation of various nanoscale composites of which nanofibers have gotten extensive consideration. Nanofibers are polymeric/composite fibers which have a nanoscale diameter. They vary in porous structure and have an extensive area. Material choice is of crucial importance for the assembly of nanofibers and their function as efficient drug and biomedicine carriers. A broad scope of active pharmaceutical ingredients can be incorporated within the nanofibers or bound to their surface. The ability to deliver small molecular drugs such as antibiotics or anticancer medications, proteins, peptides, cells, DNA and RNAs has led to the biomedical application in disease therapy and tissue engineering. Although nanofibers have shown incredible potential for drug and biomedicine applications, there are still difficulties which should be resolved before they can be utilized in clinical practice. This review intends to give an outline of the recent advances in nanofibers, contemplating the preparation methods, the therapeutic loading and release and the various therapeutic applications.