Citations

ABSTRACT Our study aimed to develop a novel, reproducible, minimally invasive turkey knee osteoarthritis (OA) model and evaluate whether intra‐articular hyaluronan (HA) alone or combined with purified exosome product (PEP) attenuates OA‐related functional and structural deterioration. OA was induced arthroscopically by transection of the anterior and posterior cruciate ligaments with resection of the anterior horn of the medial meniscus. Animals received intra‐articular injections of saline, HA, or PEP + HA at postoperative 2–5 weeks. Gait was assessed at 4, 8, and 12 weeks, and cartilage degeneration, subchondral bone sclerosis, osteophyte formation, synovial fibrosis, heterotopic ossification, and meniscal integrity were evaluated by quantitative CT and histology at week 12. Compared with saline, HA improved lameness, preserved cartilage glycosaminoglycan content, and reduced meniscal rupture, subchondral bone sclerosis, and periarticular heterotopic ossification. PEP + HA provided additional benefits, including prolonged stance phase, reduced synovial fibrosis, and greater chondroprotection than HA alone, while plantar pressure variables, subchondral bone remodeling, and patellar osteophytes did not differ between HA and PEP + HA. This turkey model reliably produces human‐like OA changes and enables longitudinal functional and structural assessment. Intra‐articular HA mitigated OA progression, and the addition of PEP conferred incremental joint protection.

ABSTRACT Extracellular vesicles (EVs) are non‐replicating, lipid membrane‐bound nanoparticles released by most eukaryotic cells into the extracellular space. When derived from platelets, a subset of EVs can exhibit remarkable anti‐inflammatory and antioxidant properties, making them attractive candidates to attenuate sterile inflammatory states such as limb skeletal muscle ischaemia‐reperfusion injury (IRI). Peripheral extremity IRI complicating acute limb revascularisation procedures, replantation of major traumatic amputations and limb allotransplants can trigger a life‐threatening reperfusion syndrome that leads to multi‐organ system failure and death. In this study, we used a platelet‐derived EVs‐enriched preparation as a therapeutic strategy for extremity IRI. To allow for a clinically translatable drug delivery strategy, we established and validated a catheter‐directed regional intra‐arterial limb infusion (RLI) delivery approach that permitted selective and effective targeting of pEVs to limb skeletal muscles and soft tissues in the vascularly isolated rodent extremity simulating pre‐reperfusion preservation and revascularisation conditions of the ischaemic or amputated extremity. In addition to being safe and feasible, we demonstrated robust retention of EVs by skeletal muscles of the operative limb during the early critical phase of reperfusion injury following RLI. We also show that pretreatment of ischaemic skeletal muscles using an pEVs‐enriched formulation just before reestablishing extremity blood flow alleviated metabolic derangements and suppressed the systemic and localised proinflammatory cytokine response associated with skeletal muscle reperfusion and reduced histologic markers of myofibre injury without adverse effects on serum chemistries. This work opens a new perspective to investigate novel approaches for regional delivery of therapeutic pEVs to skeletal muscle to mitigate limb IRI in vivo, and to achieve both in situ and ex vivo targeted delivery of nanocarriers to the isolated limb tissue for other therapeutic applications.

Background: Healing of the tendon-bone interface (TBI) after rotator cuff injury is limited, often leading to scar-mediated repair. Decellularized tendon fibrocartilage–bone composite (dTFBC) and bone marrow mesenchymal stem cell sheets (BMSCS) improve repair in preclinical models, but full scaffold encapsulation with mechanical preconditioning remains unexplored. Purpose: To evaluate TBI regeneration using mechanically preconditioned, BMSCS-encapsulated dTFBC scaffolds in a rabbit model. Study Design: Controlled laboratory study. Methods: A total of 48 male New Zealand White rabbits were randomized into 4 groups (n = 12 each): (1) standard repair (control); (2) repair with dTFBC; (3) repair with dTFBC-BMSCS; and (4) repair with mechanically preconditioned dTFBC-BMSCS (mdTFBC-BMSCS). Healing at 12 weeks was assessed via gross observation, histomorphological and immunohistochemical analyses, and biomechanical testing. Results: The mdTFBC-BMSCS group demonstrated a higher ultimate failure load (mean, 203.9 ± 65.6 N) than both the control (118 ± 37.4 N; P = .003) and dTFBC groups (127 ± 44.1 N; P = .008), with no significant difference between the 2 BMSCS-treated groups. Histological analysis revealed enhanced fibrocartilage formation, improved collagen fiber organization, and reduced inflammation infiltration at the TBI in the mdTFBC-BMSCS group. Immunohistochemical analysis showed greater collagen type 2 alpha 1 chain-, interleukin 10-, and arginase 1-positive areas in the mdTFBC-BMSCS group than in the control and dTFBC groups. Conclusion: Mechanically preconditioned, fully BMSCS-encapsulated dTFBC scaffolds promoted TBI regeneration, with enhanced cellular integration, fibrocartilage formation, and favorable biomechanical performance. Clinical Relevance: This biomimetic scaffold strategy may enhance biological healing and reduce the risk of retear after rotator cuff repair.

Chronic wounds remain a major unmet clinical challenge, often failing to progress to normal healing due to persistent inflammation, impaired angiogenesis, and cellular senescence. Exosomes have recently been investigated as promising acellular therapeutics capable of restoring intercellular communication and promoting tissue regeneration. Among these, the Purified Exosome Product (PEP) represents a next-generation, platelet-derived exosome formulation manufactured under Good Manufacturing Practice (GMP) conditions with high purity, stability, and reproducibility. This review summarizes the current advances in exosome-based chronic wound therapeutics and PEP delivery systems and their translational potentials. Incorporation of PEP into bioengineered carriers such as fibrin sealant, collagen scaffolds, and hyaluronic acid (HA) hydrogels enables localized and sustained exosome release, significantly prolonging therapeutic effects and improving regenerative outcomes. Fibrin-based PEP delivery achieved complete wound closure and functional skin regeneration in animal models, while collagen and HA-based systems showed promising results for injectable and dermatologic applications. Beyond its intrinsic healing effects, PEP may also serve as a nanocarrier for other drugs, offering a future direction in chronic wound management.

Background: Rupture at tendon repair sites in animal models impedes the study of healing. To address this, we investigated “safe incisions” – strategic partial transections to prevent rupture under excessive force. We hypothesized these would act as mechanical “fuses,” reducing repair site tension. Objectives: This in vitro biomechanical study optimized safe incision spacing to enhance tendon construct strength and minimize gap formation in a turkey flexor tendon model. Materials and Methods: Forty turkey flexor tendons were divided into five groups ( n = 8): Repaired without incisions, intact with 5 mm incisions, repaired with 5 mm incisions, intact with 10 mm incisions, and repaired with 10 mm incisions. Repairs used a modified Pennington suture. Safe incisions (opposing hemi-transections) with 5 mm or 10 mm longitudinal spacing were created proximally. Tendons were tested to failure at 1 mm/s, recording force-elongation, failure mode, gap formation (>2 mm at 10% strain), stiffness, and repair site elongation. Results: Repaired tendons without incisions (Group 1) showed 100% repair site failure (46.5 ± 10.96 N). With 5 mm safe incisions (Group 3), no repair site failures occurred (incision failure at 18.11 ± 10.96 N). 10 mm incisions (Group 5) offered partial protection (25% repair failure at 37.48 ± 11.35 N). Group 1 had higher gap formation (75% vs. 0% in Group 3, P < 0.01), stiffness, and repair site elongation than Groups 3 and 5. Gap formation force was similar for Group 1 (25.76 ± 9.18 N) and Group 5 (25.04 ± 12.21 N). Conclusions: In this in vitro model, 5 mm spaced safe incisions effectively shifted failure away from the repair and limited gap formation by reducing stiffness. 10 mm incisions provided partial protection. Strategically placed safe incisions show potential to protect tendon repairs from immediate rupture by enabling controlled lengthening at a weaker site. However, tendinopathy risk and clinical relevance require in vivo studies.

ABSTRACT Calcific tendinopathy is a common musculoskeletal disorder marked by calcium deposition within tendons, often accompanied by pain, impaired mobility, and in severe cases, ossification. However, the mechanisms underlying tendon mineralization remain poorly understood. In contrast to pathological human calcification, turkeys naturally develop tendon mineralization during growth without signs of inflammation or ossification. This study had two phases: an observational phase to assess onset and progression of calcification, and an interventional phase to evaluate the role of mechanical loading. In the observational phase, flexor tendons were collected from turkeys aged 1–16 weeks in a serial sacrifice study and analyzed by Von Kossa staining and biomechanical testing. Calcification began at 7 weeks, localized within organized collagen matrices, progressed through Weeks 8–14, and peaked by 16 weeks. In the interventional phase, nine female turkeys were randomized at 4 weeks into a transection group ( n = 3), sham group ( n = 3), and control group ( n = 3). Transection at the muscle–tendon junction eliminated mechanical loading. At 16 weeks, tendons were analyzed by histology, quantitative RT‐PCR, ICP‐MS, and biomechanical testing. Transected tendons showed a near‐complete absence of mineralization, reduced expression of osteogenic markers (osteopontin, osteocalcin, Runx‐2), and significantly lower calcium, magnesium, and phosphorus levels. Biomechanical testing indicated reduced stress relaxation, stiffness, and Young's modulus in the transected group. Tendon calcification in turkeys functioned as a mechanically regulated, nonpathological process. The study established a relevant model for early tendon mineralization and offered a basis for developing load‐dependent therapies for human tendon disease.

Abstract Column-type wrists, which exhibit increased scaphoid flexion during radial deviation, often experience greater loss of motion after periscaphoid arthrodesis compared with row-type wrists. Dynamic radiographic series are typically used to differentiate these kinematic patterns. In this study, we evaluate capitate morphology as a means of predicting column- or row-type carpal kinematics. This study investigated whether wrist kinematic patterns could be predicted using simple anteroposterior (AP) radiographs. We hypothesized that capitate morphology, given its close articulation with the scaphoid, influences these patterns. We analyzed 75 wrist motion radiographic series from 45 patients. Capitates were classified as either Type I (rectangular) or Type II (pentagonal) based on their shape. Wrist kinematic patterns were categorized as row- or column-type based on the degree of scaphoid length shortening during radial deviation. Our analysis revealed that a Type II capitate was a significant predictor of column-type wrists, with an odds ratio of 6.01 compared with Type I (p = 0.014). Furthermore, Type II capitates were associated with increased scaphoid flexion and reduced translation. Capitate morphology, as assessed from a plain AP radiograph, can serve as an easily accessible marker and reliable predictor of wrist motion patterns. This could potentially aid in surgical planning and patient counseling, particularly when dynamic radiographic series are not feasible. Diagnostic, Level III.

Background: Tendon-bone healing after rotator cuff injury is, or remains, a clinical challenge. Purpose: To examine the role of intraoperative use of purified exosome products (PEPs) in the treatment of rotator cuff injuries and to assess the effect of PEP on supraspinatus tendon-bone healing after rotator cuff repair in a rat model. Study Design: Controlled laboratory study. Methods: This study used 120 Sprague-Dawley rats that underwent an acute supraspinatus tendon transection from the insertion, followed by repair using a single transosseous suture. They were divided into 3 groups: a control group that received only sutures, a TISSEEL group that used a commercially available fibrin sealant patch (TISSEEL) of approximately 0.5 cm 2 , and a PEP-TISSEEL group that used a similarly sized TISSEEL patch combined with PEP. Autopsies were performed at 1, 3, 6, and 8 weeks after surgery. Analyses were performed using molecular biological, biomechanical, and histological techniques. Results: At 6 weeks, the PEP-TISSEEL group achieved greater failure load (mean, 27.5 ± 5.3 N) than the control (mean, 16.4 ± 4.2 N; P = .012) and TISSEEL (mean, 23.4 ± 5.0 N; P = .041) groups, with superiority persisting at 12 weeks (27.2 ± 6.5 N vs 13.1 ± 2.6 N [ P = .002] for the control group and 21.1 ± 5.8 N [ P = .037] for the TISSEEL group). DigiGait showed earlier recovery of stride length and paw angle. Histology revealed organized collagen and reduced scarring, while molecular assays demonstrated early inflammatory modulation with subsequent upregulation of collagen type 1 or 3 and TGF-β, supporting accelerated tendon-bone healing. Conclusion: Intraoperative application of PEP-TISSEEL enhanced tendon-bone healing in a rat model by improving biomechanical strength, promoting enthesis-specific histological regeneration, and accelerating functional recovery as evidenced by gait analysis. Clinical Relevance: The intraoperative application of PEP combined with TISSEEL significantly enhances rotator cuff tendon healing by modulating early inflammation, promoting collagen synthesis, and improving biomechanical properties in a rat model. These findings suggest that PEP-based therapies could offer a promising adjunct in surgical repair, potentially reducing retear rates and improving functional outcomes in patients with rotator cuff injuries. Further clinical studies are warranted to translate these benefits into human applications.

ABSTRACT Tendon adhesion is a major complication following tendon reconstruction surgery in the hand. Previous studies showed that a combination of hyaluronic acid (HA) and gelatin, covalently bound to the tendon surface, can provide a durable gliding surface to reduce adhesions in animal models both in‐vitro and in‐vivo. We have developed a similar product using good manufacturing practice (GMP) standards, in preparation for use in humans. This study aimed to examine the frictional properties and elastic modulus of the Manufactured Tendon Lubricant (MTL) when applied to an extrasynovial canine peroneus longus (PL) tendon in‐vitro. Twenty PL tendons along with the 2nd and 5th digits from adult canine forepaws, were obtained (mean age: 12 months, weight: 35 kg) from animals sacrificed in Institutional Animal Care and Use Committee (IACUC) approved protocols. Tendons were treated either with the MTL or saline solution, as a control. Eight tendons from each group (MTL vs saline‐treated) underwent friction testing, using a previously described protocol, followed by indentation testing to assess tendon elastic modulus (a marker of successful crosslinking). Two tendons from each group were not tested and were sent for scanning electron microscopy (SEM). The MTL group had significantly ( p < 0.001) lower friction and gliding resistance as well as higher elastic modulus of the PL tendons, compared to the saline group. This study demonstrates that MTL provides lubricating effects and fixation to the tendon surface and may be suitable for human testing.

Introduction: This study investigated the association between capitate morphology and the success rates of non-vascularized bone graft (NVBG) and vascularized bone graft (VBG) operations for scaphoid nonunion. Methods: We retrospectively analysed 213 patients with established scaphoid non-union who underwent either non-vascularized bone graft ( n = 75) or vascularized bone graft ( n = 138). We analysed risk factors, including demographics, medical history, implant type, previous surgery, bone graft donor site and capitate morphology for their association with treatment outcome. We also assessed the relationship between capitate and scaphoid morphology in the uninjured wrists of 31 patients. Results: The overall success rate was 81% for NVBG and 86% for VBG, with no significant difference. For NVBG, Type II capitate, age 40 or older and tobacco use were significant risk factors for failure. For VBG, only previous surgery was a significant risk factor. In uninjured wrists, a Type II capitate was associated with a significantly thinner scaphoid waist and a lower waist index than a Type I capitate. Conclusion: Our study introduces a new radiographic classification of capitate morphology and establishes its significant association with scaphoid morphology. Beyond traditional factors, capitate morphology can help to assess scaphoid morphology and potentially infer vascularity, aiding the selection of the most appropriate bone graft type for treating scaphoid non-union. Level of evidence: III