Rotator Cuff Regeneration Research Articles

Drug-free extracellular vesicles: A spatiotemporally controlled release engineering strategy for osteogenesis and anti-inflammatory niches in rotator cuff regeneration

Natural small-molecule drugs have promising potential to promote tissue regeneration in various fields. Therefore, maximizing drug efficiency while minimizing potential side effects is imperative. Peiminine, a natural product extracted from natural Fritillaria, is one of small-molecule drugs in the field of bone regeneration due to its good bone-promoting and anti-inflammatory abilities. However, its application is limited by a lack of biological activity, poor biocompatibility at high concentrations, and difficulty in achieving long-term slow-release and therapeutic effects. Extracellular vesicles (EVs) produced by preconditioned cells are considered to have special biological functions, and their potential to further retain, buffer, and transmit drug effects and expand the therapeutic effect has been widely studied. Thus, our study provides a drug-free bioengineering strategy by preconditioning bone marrow mesenchymal stem cells (BMSC) with Peiminine, then EVs, secreted as Peim-EVs, were extracted and combined with a decellularized extracellular matrix (dECM). The final EVs-dECM system with a spatiotemporally controlled release system was formed. In vitro studies demonstrated that Peim-EVs solved the problem of Peiminine biocompatibility and exhibited osteogenic and anti-inflammatory effects, which may be related to PI3K/AKT, MAPK/NF-κB, and Hippo signaling pathways. An in vivo model of rotator cuff injury in rats also showed that EVs-dECM had a good effect on rotator cuff repair. Combined with engineering strategy, this study provides verification and scenario expansion for drug application, especially for drug-free strategies that retain the biological effects of drugs, and has broad significance.

Engineered Tendon-Fibrocartilage-Bone Composite With Mechanical Stimulation for Augmentation of Rotator Cuff Repair: A Study Using an In Vivo Canine Model With a 6-Month Follow-up

Background: Rotator cuff repair augmentation using biological materials has become popular in clinical practice to reduce the high retear rates associated with traditional repair techniques. Tissue engineering approaches, such as engineered tendon-fibrocartilage-bone composite (TFBC), have shown promise in enhancing the biological healing of rotator cuff tears in animals. However, previous studies have provided limited long-term data on TFBC repair outcomes. The effect of mechanical stimulation on TFBC has not been explored extensively. Purpose: To evaluate functional outcomes after rotator cuff repair with engineered TFBC subjected to mechanical stimulation in a 6-month follow-up using a canine in vivo model. Study Design: Controlled laboratory study. Methods: A total of 40 canines with an acute infraspinatus (ISP) tendon transection model were randomly allocated to 4 groups (n =10): (1) unilateral ISP tendon undergoing suture repair only (control surgery); (2) augmentation with engineered TFBC alone (TFBC); (3) augmentation with engineered TFBC and bone marrow-derived stem cells (BMSCs) (TFBC+C); and (4) augmentation with engineered TFBC and BMSCs, as well as mechanical stimulation (TFBC+C+M). Outcome measures—including biomechanical evaluations such as failure strength, stiffness, failure mode, gross appearance, ISP tendon and muscle morphological assessment, and histological analysis—were performed 6 months after surgery. Results: As shown in the mechanical test, the TFBC+C+M group exhibited higher failure strength compared with other repair techniques. The most common failure mode was avulsion fracture in the TFBC+C+M group, but tendon-bone junction rupture was observed predominantly in different groups. Engineered TFBC with mechanical stimulation showed over 70% relative failure strength compared with normal ISP, and the other groups showed about 50% relative failure strength. Histological analysis revealed less fat infiltration and closer-to-normal muscle fiber structure in the mechanical stimulation group. Conclusion: This study provides evidence that mechanical stimulation of engineered TFBC promotes rotator cuff regeneration, thus supporting its potential for rotator cuff repair augmentation. Clinical Relevance: This study provides valuable evidence supporting the use of a novel tissue-engineered material (TFBC) in rotator cuff repair and paves the way for advancements in the field of rotator cuff regeneration.

Comparison of the efficacy of two-dimensional and three-dimensional cultures of human rotator cuff-derived mesenchymal stem cells for rotator cuff regeneration

Comparison of the efficacy of two-dimensional and three-dimensional cultures of human rotator cuff-derived mesenchymal stem cells for rotator cuff regeneration

Engineered Metallic Ion-Based Hydrogel for Tendon-Bone Reconstruction.

Rotator cuff regeneration is hindered by compromised vascular architecture, inflammation, and instability of the reconstructed tendon-bone interface. Herein, inspired by the phenomenon of magnetic clasps being connected together by a specific structure, an engineered metallic ion-based hydrogel scaffold was constructed through a bioorthogonal click reaction between (DOPA)4-PEG5-N3 and DBCO-BMP-2 peptides and a photopolymerization process in the hydrogel matrix, exhibiting the potential for angiogenesis, bone regeneration, and modulation of the inflammatory milieu, which aimed at facilitating rotator cuff regeneration. In vitro studies showed that the composite hydrogel scaffold stimulated the angiogenic activity of human umbilical vein endothelial cells and osteogenic differentiation of bone marrow mesenchymal stem cells, transforming macrophages from M1 to M2. Moreover, imaging and immunohistochemical analysis of a rat rotator cuff injury models demonstrated that the composite hydrogel could effectively promote regeneration and exhibit remarkable biocompatibility. In summary, this composite hydrogel material established an effective platform for the release of metal ions and clickable peptides, which accelerated the regeneration of rotator cuff injuries and had broad prospects for application in rotator cuff therapy.

Collagen and platelet-rich plasma in partial-thickness rotator cuff injuries. Friends or only indifferent neighbours? Randomised controlled trial

BackgroundPartial-thickness rotator cuff injuries (PTRCI) are the sum of degenerative, overload, and microtrauma processes. An external supply of collagen and platelet-rich plasma (PRP) could potentially counteract the deterioration of degenerative tendinopathy. This study aimed to compare the effectiveness of collagen with PRP, PRP alone, and collagen alone in the treatment of PTRCI.MethodsNinety patients with PTRCI were randomised and treated with ultrasound-guided injections into the shoulder bursa every consecutive week: Group A – collagen with PRP (n = 30), Group B – collagen alone (n = 30), and Group C – PRP alone (n = 30). Primary outcomes were pain intensity measured in control points on a numeric rating scale (NRS), QuickDash, and EQ-5D-5L questionnaires at the initial assessment (IA) and control assessments after 6 (T1), 12 (T2), and 24 (T3) weeks, respectively.ResultsNo statistical differences were found between groups in primary outcomes, although there was a trend towards improvement in Groups A and C (opposite to Group B) between T2 and T3. The following parameters were also observed: rotator cuff discontinuity (n = 3, one case in each group) and rotator cuff regeneration (n = 22 in Group A, n = 20 in Group B, and n = 23 in Group C).ConclusionsCombined therapy of collagen and PRP in PTRCI presents similar effectiveness to monotherapies with collagen or PRP.Trial registrationThe study was prospectively registered on the NCT Trial Center (identification number: NCT04492748) on 30.07.2020.

3D cell-printing of gradient multi-tissue interfaces for rotator cuff regeneration.

Owing to the prevalence of rotator cuff (RC) injuries and suboptimal healing outcome, rapid and functional regeneration of the tendon–bone interface (TBI) after RC repair continues to be a major clinical challenge. Given the essential role of the RC in shoulder movement, the engineering of biomimetic multi-tissue constructs presents an opportunity for complex TBI reconstruction after RC repair. Here, we propose a gradient cell-laden multi-tissue construct combined with compositional gradient TBI-specific bioinks via 3D cell-printing technology. In vitro studies demonstrated the capability of a gradient scaffold system in zone-specific inducibility and multi-tissue formation mimicking TBI. The regenerative performance of the gradient scaffold on RC regeneration was determined using a rat RC repair model. In particular, we adopted nondestructive, consecutive, and tissue-targeted near-infrared fluorescence imaging to visualize the direct anatomical change and the intricate RC regeneration progression in real time in vivo. Furthermore, the 3D cell-printed implant promotes effective restoration of shoulder locomotion function and accelerates TBI healing in vivo. In summary, this study identifies the therapeutic contribution of cell-printed constructs towards functional RC regeneration, demonstrating the translational potential of biomimetic gradient constructs for the clinical repair of multi-tissue interfaces.

Pegylated insulin-like growth factor-1 biotherapeutic delivery promotes rotator cuff regeneration in a rat model.

Tears in the rotator cuff are challenging to repair because of the complex, hypocellular, hypovascular, and movement-active nature of the tendon and its enthesis. Insulin-like Growth Factor-1 (IGF-1) is a promising therapeutic for this repair. However, its unstable nature, short half-life, and ability to disrupt homeostasis has limited its clinical translation. Pegylation has been shown to improve the stability and sustain IGF-1 levels in the systemic circulation without disrupting homeostasis. To provide localized delivery of IGF-1 in the repaired tendons, we encapsulated pegylated IGF-1 mimic and its controls (unpegylated IGF-1 mimic and recombinant human IGF-1) in polycaprolactone-based matrices and evaluated them in a pre-clinical rodent model of rotator cuff repair. Pegylated-IGF-1 mimic delivery reestablished the characteristic tendon-to-bone enthesis structure and improved tendon tensile properties within 8 weeks of repair compared to controls, signifying the importance of pegylation in this complex tissue regeneration. These results demonstrate a simple and scalable biologic delivery technology alternative to tissue-derived grafts for soft tissue repair.

The Role of Nanomaterials and Biological Agents on Rotator Cuff Regeneration.

The rotator cuff is a musculotendon unit responsible for movement in the shoulder. Rotator cuff tears represent a significant number of musculoskeletal injuries in the adult population. In addition, there is a high incidence of retear rates due to various complications within the complex anatomical structure and the lack of proper healing. Current clinical strategies for rotator cuff augmentation include surgical intervention with autograft tissue grafts and beneficial impacts have been shown, but challenges still exist because of limited supply. For decades, nanomaterials have been engineered for the repair of various tissue and organ systems. This review article provides a thorough summary of the role nanomaterials, stem cells and biological agents have played in rotator cuff repair to date and offers input on next generation approaches for regenerating this tissue.

Subacromial bursal preservation can enhance rotator cuff tendon regeneration: a comparative rat supraspinatus tendon defect model study

The role of subacromial bursa in rotator cuff surgery is unknown. This study aimed to assess the subacromial bursa's role in the healing of supraspinatus tendon injury in a rat model. Twenty-three male Sprague-Dawley rats (9 weeks old; weight, approximately 296 g) were used in this study. Three rats used as biomechanical study controls were killed at 12 weeks of age. A supraspinatus tendon defect was made bilaterally in 20 rats, whereas an additional subacromial bursa sectioning was performed on the left side. Six rats were killed for biomechanical testing and 4 were killed for histologic observation at 3 and 9 weeks, respectively. The regenerated tendon in the bursal preservation group showed significantly superior biomechanical properties in maximum load to failure at 3 and 9 weeks and stiffness at 9 weeks after surgery compared with the bursal removal group. The modified Bonar scale scores showed better regenerated supraspinatus tendons in the bursal preservation group. The present study found that the subacromial bursa plays an important role in rotator cuff regeneration in this rat supraspinatus injury model. Extensive bursectomy of the subacromial bursa may not be recommended in rotator cuff repair surgery, though future invivo human studies are needed to confirm these observations.

Macroporous 3D Scaffold with Self-Fitting Capability for Effectively Repairing Massive Rotator Cuff Tear.

The postoperative retear rate of direct repair of massive rotator cuff tear has risen up to 40% because of the dissatisfied tendon-to-bone healing and poor regenerative potential of remnant rotator cuff tissue. A biological scaffold that connects the remnant rotator cuff tissue and bone might be a promising substitute. In the present study, we have developed a macroporous three-dimensional scaffold poly(ester-urethane)urea (PEUU), with self-fitting capability employing thermally induced phase separation (TIPS) technique. The scaffold provides oriented connected macropores for cells migration, and promoted tendon-to-bone healing on the basis of surgical repair. The scaffolds were characterized by scanning electron microscopy, stress-strain test and cell biocompatibility study. In vitro studies exhibited that PEUU scaffold with suitable elastic mechanical properties can better support proliferation and migration of rabbit bone mesenchymal stem cells (RBMSCs). After three months postreconstruction of massive rotator cuff tear in a rabbit model using PEUU scaffold, there was complete regeneration of rotator cuff with physical tendon-to-bone interface and continuous tendon tissue, as observed from histological analysis. Further, biomechanical testing demonstrated that rotator cuff induced by PEUU scaffold had no significant difference as compared to normal rotator cuff. This macroporous, mechanically matched scaffold is potentially suitable for the application in massive rotator cuff repair. In conclusion, this study demonstrates the high efficiency of the macroporous 3D scaffold with self-fitting capability in facilitating rotator cuff regeneration.

The application of BMP-12-overexpressing mesenchymal stem cells loaded 3D-printed PLGA scaffolds in rabbit rotator cuff repair

This study investigates if the application of bone marrow-derived mesenchymal stem cells (BM-MSCs) loaded 3D-printed scaffolds could improve rotator cuff repair. The polylactic-co-glycolic acid (PLGA) scaffolds were fabricated by 3D print technology. Rabbit BM-MSCs were transfected with a recombinant adenovirus encoding bone morphogenic protein 12 (BMP-12). The effect of BM-MSCs loaded PLGA scaffolds on tendon-bone healing was assessed by biomechanical testing and histological analysis in a rabbit rotator cuff repair model. We found that the PLGA scaffolds had good biocompatible and biodegradable property. Overexpression of BMP-12 increased the mRNA and protein expression of tenogenic genes in BM-MSCs cultured with DMEM medium and seeded in PLGA scaffolds. When BMP-12-overexpressing BM-MSCs-loaded PLGA scaffolds were implanted into the injured rabbit supraspinatus tendon-bone junctions, the tendon-bone healing was improved. Our results suggest that application of BMP-12 overexpressing BM-MSCs loaded 3D-printed PLGA scaffolds promote the healing of tendon-bone interface, improve collagen organization and increase fibrocartilage in the rabbit rotor cuff repair. Rotator cuff regeneration achieved by BMP-12-overexpressing BM-MSCs-loaded PLGA scaffolds may represent a novel approach for the management of rotator cuff defect.

Bridging Repair of Large Rotator Cuff Tears Using a Multilayer Decellularized Tendon Slices Graft in a Rabbit Model

The purpose of this study was to evaluate the efficacy of an extracellular matrix scaffold with multilayer decellularized tendon slices (MDTSs) for reconstructing large rotator cuff tears in a rabbit model. Large defects in the infraspinatus tendons were created bilaterally in 36 rabbits. The graft group underwent bridging repair of the defects with the MDTSs grafts from Achilles tendons of adult beagle dogs, and the control group underwent repair with the autologous excised tendon. Specimens underwent histologic observation, biomechanical testing, and microcomputed tomography analysis at 2, 4, and 8weeks after surgery. Histologic analysis confirmed that the MDTSs graft promoted cell ingrowth and tissue integration, and fibrocartilage and Sharpey fibers formed at the enthesis at 8weeks. Accordingly, the MDTSs graft generated a histologic appearance similar to that of the autogenous tendon graft. Mechanical testing revealed a significant increase of the regenerated tendons in ultimate load and stiffness from 4 to 8weeks postoperatively, which was similar to autologous tendon repair. Microcomputed tomography analysis demonstrated that the MDTSs graft promoted bone formation at the tendon-bone insertion, thus improving the mechanical properties of the repair tendon. The MDTSs graft used to bridge large rotator cuff defects in a rabbit model promoted host cell ingrowth, enhanced the remodeling of regenerated tendon, and promoted fibrocartilage formation, thus improving the biomechanical properties of the repaired tendon. This study thereby provides fundamental information for rotator cuff regeneration with the MDTSs graft. Rotator cuff regeneration using MDTSs grafts is a promising procedure for large rotator cuff tears.

Amniotic membrane improves force production after repair of a massive rotator cuff tear

Rotator cuff tears are a common cause of upper extremity disability, with nearly 250,000 surgical repairs performed annually. Chronically torn rotator cuff muscles display profound muscle atrophy, fibrosis and accumulation of fat in and around muscle fibers. Even after undergoing surgical repair, many patients continue to have persistent muscle atrophy, and re‐tear rates are 40% or more. Identifying novel therapies that can promote muscle regeneration after rotator cuff repair could lead to substantial improvements in our ability to treat chronic rotator cuff tears. Human amniotic‐derived grafts are a type of allograft that is thought to have the potential to improve tissue regeneration, although the mechanism of these products is not well characterized and to our knowledge has not been studied in respect to rotator cuff regeneration. Using a preclinical rotator cuff tear model in rats, our objective was to determine the efficacy of human amniotic derived grafts on rotator cuff muscle regeneration. To accomplish this, we induced a chronic rotator cuff tear for 30 days and then repaired the tear in the presence or absence of the human amniotic stem cell graft. We then analyzed the contractile function of muscle fibers from control and treated muscles. Muscle cross‐sectional area (CSA), maximum isometric force (Fo) and the force per cross‐sectional area, or specific force (sFo) were recorded from muscle fibers isolated from each of these groups. We hypothesized that treatment with human amniotic cell graft would improve sFo in rats compared to rats without these grafts. The CSA of the amniotic membrane repair group was 53% greater than the control repair group (p<0.01), and the Fo was also 55% higher with membrane supplementation (p<0.01). Further, sFo of the membrane repair group was 13% larger than the control repair (p=0.02). Combined, the augmentation of chronic rotator cuff repair surgery with a human amniotic derived graft in rats markedly improved muscle function. Based on this promising preclinical data, further study of human amniotic stem cell grafts in patients with chronic rotator cuff tears in warranted.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Rotator cuff healing and repair

Despite the frequency of rotator cuff tendinopathies, rotator cuff repair procedures still have high failure rates. Thus, new treatment strategies that accelerate healing and improve regeneration are needed. Tissue engineering approaches, which include the implantation of extracellular matrix scaffolds, cells, and/or growth factors, can be applied to modulate the healing process, improving biomechanical properties and functional outcomes of the repaired tendon. In particular, the microstructural properties of extracellular matrix scaffolds can influence cell migration, protein synthesis, and fiber organization in healing tendon. Through manufacturing techniques, such as three-dimensional printing, the properties of these scaffolds can be optimized for rotator cuff regeneration. In addition to scaffolds, implantation of stem cells and tenocytes has been shown to increase healing rates and reduce inflammation in animal models but has not been tested clinically. Many growth factors also are present at the wound site during healing, but studies attempting to recreate these conditions during healing with platelet-rich plasma have found little evidence supporting its use. Systematic treatments, including anti-inflammatory medication and metalloproteinase inhibitors, are commonly used in rotator cuff tendinopathies but have adverse effects that inhibit tendon healing. A variety of tissue engineering and biologic treatments for rotator cuff tendinopathy are currently being developed, but challenges still remain before they can be applied clinically.

Allogenous Tendon Stem/Progenitor Cells in Silk Scaffold for Functional Shoulder Repair

Tendon stem/progenitor cells (TSPCs) were recently identified within tendon tissues. The aim of this study was to investigate TSPC-seeded knitted silk-collagen sponge scaffold for functional shoulder repair. The multidifferentiation potential, proliferation, and immune properties of TSPCs were investigated in vitro, while the efficacy of TSPC-seeded knitted silk-collagen sponge scaffolds in promoting rotator cuff regeneration was evaluated in vivo within a rabbit model. TSPCs, which exhibited universal stem cell characteristics (i.e., clonogenicity, high proliferative capacity, and multidifferentiation potential), nonimmunogenicity, and immunosuppression, proliferated well on our scaffold in vitro. Implantation of allogenous TSPC-seeded scaffolds within a rabbit rotator cuff injury model did not elicit an immunological reaction, but instead increased fibroblastic cell ingrowth and reduced infiltration of lymphocytes within the implantation sites at 4 and 8 weeks postsurgery. After 12 weeks, the allogenous TSPC-treated group exhibited increased collagen deposition and had better structural and biomechanical properties compared to the control group. This study thus demonstrated that the allogenous TSPC-seeded knitted silk-collagen sponge scaffold enhanced the efficacy of rotator cuff tendon regeneration by differentiating into tenocytes, and by secreting anti-inflammatory cytokines that prevent immunological rejection. Hence, allogenous TSPC-seeded knitted silk-collagen sponge scaffolds can be a clinically useful application for tendon tissue engineering.

Rotator Cuff Regeneration Using a Bioabsorbable Material With Bone Marrow–Derived Mesenchymal Stem Cells in a Rabbit Model

Background: Rotator cuff regeneration using tissue engineering techniques is a challenging treatment in elderly patients with irreparable rotator cuff tears. Hypothesis: A polyglycolic acid sheet scaffold with seeded mesenchymal stem cells (MSCs) may enhance the expression of type I collagen products and increase the mechanical strength of the regenerated tendon in vivo. Study Design: Controlled laboratory study. Methods: A surgically created defect of infraspinatus tendons of rabbits was reconstructed with 2 different materials, a polyglycolic acid (PGA) sheet alone (PGA group) (n = 34) and a PGA sheet seeded with autologously cultured MSCs (MSC group) (n = 34). The authors created a tendon defect model without embedding any graft as the control model (control group) (n = 34). The rabbits were sacrificed at 4, 8, and 16 weeks after the operation and then were histologically evaluated. The rabbits were also biomechanically evaluated by measuring the ultimate failure loads and Young’s modulus at 4 and 16 weeks following implantation. Results: In the MSC group, the fibrocartilage layers and Sharpey fibers were found regularly in the insertion site at 8 weeks compared with the PGA group. In control group, thin membranes with many fibroblasts arranged in an irregular pattern linked the end of the torn cuff to the bone without any Sharpey fibers and type I collagen. A large volume of type I collagen was found in comparison with type III collagen at 16 weeks in the MSC group, whereas type III collagen was more prevalent than type I in the PGA group. The tendon maturing score in the MSC group had higher values than the PGA and control groups at 8 and 16 weeks (mean values were 21.0 ± 0.89, 24.0 ± 2.53 in the MSC group; 16.7 ± 2.25, 21.3 ± 2.42 in the PGA group; and 10.2 ± 0.98, 12.2 ± 1.72 in the control group, respectively) (P < .05). The results of the mechanical analysis revealed that the regenerated tendons in the MSC group had better tensile strength than in the PGA and control groups at 16 weeks (mean values were 3.04 ± 0.54 in the MSC group, 2.38 ± 0.63 in the PGA group, and 1.58 ± 0.13 in the control group) (P < .05). Conclusion: Bone marrow–derived MSCs were able to regenerate tendon-bone insertions and the tendon belly, including the production of type I collagen, and increased the mechanical strength of the regenerated rotator cuff tendon. Clinical Relevance: Rotator cuff regeneration using MSCs is a promising treatment for massive rotator cuff defects.

New perspectives in rotator cuff tendon regeneration: review of tissue engineered therapies

Tissue engineering may play a major role in the treatment of rotator cuff tendon lesions through replacement of an injured tendon segment. Tendons have very poor spontaneous regenerative capabilities, and despite intensive remodelling, complete regeneration is never achieved and the strength of tendon and ligaments remains as much as 30% lower than normal even months or years following an acute injury. Tendons seem to be the least complex of the connective tissues with respect to their composition and architecture and this leads to the expectation that they would be more amenable to tissue engineered approaches than other tissues. An accurate literature revision was done in order to know the state of the art of tissue engineering therapies in the field of rotator cuff regeneration. The following techniques of tissue engineering were considered: local injection of stem cells or growth factors, gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons to be further transplanted in the lesion site. So far, few experimental or clinical studies have been done on tendon tissue engineering compared to the extensive work on other tissues of orthopaedic interest, such as bone and cartilage. The existing studies are related to the following tissue engineering methodologies: gene transfer, in situ tissue engineering and in vitro production of bioengineered tendons. In our opinion the previously described literature revision showed the necessity for future studies in this area also because of recent advances in biological and bioactive scaffolds.

Rotator Cuff Regeneration with Bone Marrow-derived Mesenchymal Stem Cells--Histological and Biomechanical Evaluation--

Rotator Cuff Regeneration with Bone Marrow-derived Mesenchymal Stem Cells<BR>--Histological and Biomechanical Evaluation--

Rotator cuff regeneration using chitin fabric as an acellular matrix

Twenty-one rabbits were used to investigate the feasibility of using nonwoven chitin fabric as an acellular matrix for rotator cuff regeneration. Infraspinatus tendons were cut bilaterally to create 10 x 10-mm defects. The defect in the right shoulder was covered with chitin fabric. The contralateral defect was left free as a control. The specimens were evaluated histologically and immunohistochemically at 2, 4, 8, and 12 weeks and biomechanically at 12 weeks after surgery. The acellular matrix increased cell numbers and improved collagen fiber alignment. The regenerated tissues were composed of type III collagen. The structural properties of the grafted shoulder were significantly greater than those of the control. This study revealed that using chitin fabric as an acellular matrix has advantages in enhancing both biologic and mechanical regeneration of rotator cuff tendons.

Rotator Cuff Regeneration by Using PGA Sheet as a Scaffold with Bone Marrow-derived Mesenchymal Stem Cells

Rotator Cuff Regeneration by Using PGA Sheet as a Scaffold with Bone Marrow-derived Mesenchymal Stem Cells