Fig 1 - uploaded by An Liu
Content may be subject to copyright.
The structure of raw silk fibers and silk fibroin under SEM (×1000): sericin, the glue-like protein coating the fibroin is shown (A); after complete degumming, the underlying silk fibroins with a smooth surface and an average diameter of about 10 μm are shown (D). Gross observation of the silk-collagen scaffold: (B) the collagen sheet adheres to (E) the knitted silk fibroin mesh with pores about 1.0 mm in diameter. Structure of the silkcollagen scaffold under SEM (×100): (C) collagen sheet side and (F) the silk fibroin mesh side.
Source publication
The objective of the present study was to perform an in vivo assessment of a novel silk-collagen scaffold for anterior cruciate ligament (ACL) reconstruction. First, a silk-collagen scaffold was fabricated by combining sericin-extracted knitted silk fibroin mesh and type I collagen to mimic the components of the ligament. Scaffolds were electron-be...
Citations
... Bi et al. modified a silkcollagen scaffold with HAp at both ends. The results exhibited massive formation of more mature bone at the tendon-bone interface, more collagen I and osteocalcin deposition, bone mineral formation, and better osteoarthritis prevention in the modified group than the silk-collagen group (Bi et al., 2015). Chop fiber (CF), nanohydroxyapatite (n-HA), and silk fibroin (SF) porous hybrid scaffolds (SHCF) were produced by Jin et al. utilizing freeze-drying. ...
Silk fibroin is an important natural fibrous protein with excellent prospects for tissue engineering applications. With profound studies in recent years, its potential in tissue repair has been developed. A growing body of literature has investigated various fabricating methods of silk fibroin and their application in tissue repair. The purpose of this paper is to trace the latest developments of SF-based scaffolds for tissue engineering. In this review, we first presented the primary and secondary structures of silk fibroin. The processing methods of SF scaffolds were then summarized. Lastly, we examined the contribution of new studies applying SF as scaffolds in tissue regeneration applications. Overall, this review showed the latest progress in the fabrication and utilization of silk fibroin-based scaffolds.
... [2][3][4] The ACL exhibits a poor self-healing ability attributed partly to its intrinsic nature (impediment to cell migration) and partly to the environmental niche in which it lies (synovial fluid, poor blood supply, and clot formation). 2,[5][6][7][8][9][10] Although some authors have resurrected arthroscopic repair techniques, 11 reconstructive surgery utilizing autografts and/or allograft have traditionally been utilized to treat ACL injuries, with around 100,000 procedures performed annually within the United States. 1,3-9,12-15 However, graftbased approaches have limitations including graft rejection, disease transmission, lack of adequate blood supply, donor site morbidity, and limited availability. ...
Background: The anterior cruciate ligament (ACL) has poor healing capabilities and is the most commonly injured knee ligament. Although ACL repair is being highly studied, the current treatment involves reconstructive surgery utilizing autografts or allografts, which have limitations. The use of Mesenchymal Stem Cells (MSCs) as a possible therapeutic option has grown. ACL-derived MSCs are likely to be the best source because studies have shown that target tissue derived stem cells will better differentiate into the target tissue than the stem cells derived from non-target ones. However, the existing literature discusses only the isolation of a mixed population of MSCs. Here we present the isolation, differentiation and characterization of human ACL-derived MSCs according to the International Society for Cellular Therapy (ISCT) criteria.
The ACL tissue was enzymatically digested. Separation of MSCs from the crude mixture of cells was then performed by fluorescence activated cell sorting (FACS) analysis. The isolated population were passaged in specific induction medium to differentiate them into adipocyte, osteocytes and chondrocytes. The cells were then further characterized with respect to their growth curve, population doubling time, colony forming ability, anchorage independent growth, and cell surface markers. The cells were finally examined for their tumorigenic potential by cell cycle analysis.
Immunoprofiling via FACSs showed an average isolation rate for cells carrying MSCs markers of 5.5%. Cells exhibited spindle-shaped morphology, and immunocytochemistry confirmed the expression of appropriate cell surface markers. The growth curve showed distinct lag and log phase. Over agar assay demonstrated no anchorage independent growth, but clonogenic potential was observed post-culture on plastic Petri dishes. The cells showed a population doubling time of about 1.5 days. Oil Red O, Alizarin Red S, and Alcian Blue staining confirmed adipogenic, osteogenic and chondrogenic differentiation, respectively. Cell cycle analysis displayed more ACL-derived MSCs in G/G phase compared to BMSCs, showing that the isolates were non-tumorigenic.
The presence of MSCs within the human ACL was confirmed via ISCT criteria, paving the way for their potential use for future ACL reconstructions. Although BMSCs have been the choice for regenerative purposes, making use of MSCs derived from ACL ligament will cut down the burden of trauma one has to undergo to obtain the Bone Marrow. Moreover, it is more convenient to harvest MSCs from otherwise discarded ACL. Finally, MSCs derived from the target tissue are believed to better differentiate to the ligament tissue than the bone derived MSCs.
... In vivo animal experiments using fibroblasts from rabbit Achilles tendon in the chitosan/HA scaffold revealed less inflammation induction in vivo, and the mechanical properties of regenerated tendon/ligament tissues could stabilize the joint. A silk/collagen scaffold with collagen microsponges formed within a knitted silk scaffold has been shown to be effective for tendon and ligament repair [133][134][135][136]. Bi et al. used a silk/collagen scaffold for ACL reconstruction and found good infiltration of fibroblast-like cells in the graft. ...
... A silk/collagen scaffold with collagen microsponges formed within a knitted silk scaffold has been shown to be effective for tendon and ligament repair [133][134][135][136]. Bi et al. used a silk/collagen scaffold for ACL reconstruction and found good infiltration of fibroblast-like cells in the graft. The stiffness of the graft was much higher than that of an autograft 16-week post-operation [133]. Zheng et al. developed an aligned collagen/silk scaffold and evaluated its biomechanical performance after implantation in a rabbit massive rotator cuff tear model [136]. ...
An effective therapeutic strategy to treat tendon or ligament injury continues to be a clinical challenge due to the limited natural healing capacity of these tissues. Furthermore, the repaired tendons or ligaments usually possess inferior mechanical properties and impaired functions. Tissue engineering can restore the physiological functions of tissues using biomaterials, cells, and suitable biochemical signals. It has produced encouraging clinical outcomes, forming tendon or ligament-like tissues with similar compositional, structural, and functional attributes to the native tissues. This paper starts by reviewing tendon/ligament structure and healing mechanisms, followed by describing the bioactive nanostructured scaffolds used in tendon and ligament tissue engineering, with emphasis on electrospun fibrous scaffolds. The natural and synthetic polymers for scaffold preparation, as well as the biological and physical cues offered by incorporating growth factors in the scaffolds or by dynamic cyclic stretching of the scaffolds, are also covered. It is expected to present a comprehensive clinical, biological, and biomaterial insight into advanced tissue engineering-based therapeutics for tendon and ligament repair.
... The LT was chosen due to the ease of harvest, length, and minimal donor site morbidity. The grafts of LT, semimembranosus tendon and patellar ligaments are the most commonly used in rabbits, especially for replacing the cranial cruciate ligament (Bi et al., 2015;Giordano et al., 2015). LT is most recommended in immature skeletons due to the risk of physeal closure and bone deformity with a patellar tendon graft (Giordano et al., 2015). ...
... In one study of rabbits with intraarticular semitendinosus autograft positioned through tibial and femoral holes observed the blending of the graft to the fibrous connective tissue over time that adhered to bony trabeculae (Blickenstaff, Grana & Egle, 1997). Healing of tendon-bone interface aiming at an effective ligament reconstruction can be slowed because of the blood supply deficit due to vascular and bone loss in the drilling site (Bi et al., 2015). In the present study, a partial adhesion of collagen fibers to the periosteum was found 90 days after surgery, suggesting an effect of surgical injury. ...
Background
Ligamentum teres (LT) has traditionally been considered a vestigial or redundant structure in humans; however, based on new studies and the evolution of hip arthroscopy, the LT injury has been viewed as a source of hip pain. Therefore, LT reconstruction can be beneficial in some cases. Rabbits have been frequently used as a model for cranial cruciate ligament reconstruction but few studies are available for ligamentum teres reconstruction.
Objective
To evaluate the semitendinosus tendon to replace ligamentum teres with the toggle technique, using rabbits as an experimental model.
Methods
Twenty-six female Norfolk rabbits with approximately 3 months of age were divided into two equal groups after excision of ligamentum teres (LT) from the right hip joint: G1—no reconstruction of LT and capsulorrhaphy; G2—double—bundle reconstruction of the LT using semitendinosus tendon autograft. In both groups, the LT was removed from the right hip joint. In G2 the autograft was harvested from the left hind limb of the same rabbit. The rabbits were evaluated clinically at different time intervals; before surgery (M1), 48 h (M2), 15 days (M3), 30 days (M4) and 90 days (M5) after surgery.
Results
The rabbits supported their limbs on the ground in both the groups. As complications of the procedure, four hip joints showed subluxations in the radiographic evaluation of G1; three at M4 and one at M5. In G2; two luxations of hip joints at M3 and one subluxation at M4 were seen. On ultrasound, irregular articular surface was seen in 30.8% of the rabbits that had subluxation of hip joints. Gross evaluation identified tendon graft integrity in 76.92% of the rabbits. Histological analysis revealed graft adhesion to the bone in the early phase comprised of sharpey-like collagen fibers.
Conclusion
The double-bundle reconstruction of the LT using autologous semitendinosus tendon associated with the toggle rod shows an early phase of tendon graft ligamentization at 90 days post-operatively in young rabbits, but biomechanical bias suffered by the tendon during gait must be considered.
... As PRF is an autologous substance, it caused severe tissue reactions in the treated tendon and surrounding tissue that included inflammation, adhesions, edema, and distortions. According to previous studies [41][42][43][44] , collagen deposition and angiogenesis are considered important factors for tendon healing. Another study 29 found that PRF increases the production of different types of tendon proteins, especially collagen. ...
This study investigated the effect of the silver nanoparticles (AgNPs) and platelet-rich fibrin (PRF) in the healing of the severed superficial digital flexor tendon in donkeys (SDFT). Twenty-seven adult donkeys were used in the study. The animals were divided into three equal groups. The first group (control group) in which the severed SDFT was sutured without the addition of any adjuvant. In the second group, there was a suture of severed SDFT with the addition of 1 ml of 1 mM silver nanoparticles (AgNPs group). The third group was subjected to the cutting of SDFT and then the addition of PRF after its suture. Each group of animals was divided into three equal subgroups that were examined after 1, 2, and 3 months. Each group of animals was clinically evaluated by assessing lameness. Gross and microscopic examinations of the healed tendons were performed after 1, 2, and 3 months of surgery. In comparison to the control group, the lameness degree decreased in the PRF and AgNPs groups, particularly in the third month after surgery. Furthermore, the lameness decreased significantly after the 3rd month relative to the 1st-month lameness in the AgNPs group. Interestingly, it was found that the PRF and AgNPs enhanced cell alignment and collagen deposition at the site of tendon injury, particularly among third-month subgroups. Therefore, it could be concluded that the PRF and AgNPs are effective materials for enhancing SDFT healing in donkeys.
... After extraction, collagen would be dissolved in a buffer solution that was then used to make collagen enthesis scaffolds using various methods. [143][144][145][146][147][148][149][150][151][152][153][154][155] The electrospun collagen enthesis scaffold, an easily accessible scaffold fabricated using an electrospinning device, is one of the most commonly used TE scaffolds and it effectively supports enthesis regeneration. 38,117 Based on the poly(ϵ-caprolactone) (PCL) electrospun nanofiber membrane scaffold fabricated using a simple PCL organic solution, Lin et al. added a collagen I (COL-1) solution into PCL solution and successfully fabricated a new type of a COL-1/PCL hybrid nanofiber membrane scaffold. ...
Enthesis, the interfacial tissue between a tendon/ligament and bone, exhibits a complex histological transition from soft to hard tissue, which significantly complicates its repair and regeneration after injury. Because traditional surgical treatments for enthesis injury are not satisfactory, tissue engineering has emerged as a strategy for improving treatment success. Rapid advances in enthesis tissue engineering have led to the development of several strategies for promoting enthesis tissue regeneration, including biological scaffolds, cells, growth factors, and biophysical modulation. In this review, we discuss recent advances in enthesis tissue engineering, particularly the use of biological scaffolds, as well as perspectives on the future directions in enthesis tissue engineering.
... According to the previous studies [41][42][43][44], collagen deposition and angiogenesis are considered important factors for tendon healing. The PRF in another study [29] has been found to increase the production of different types of tendon proteins, especially collagen. ...
This study investigated the effect of the silver nanoparticles (AgNPs) and platelet-rich fibrin (PRF) in the healing of the severed superficial digital flexor tendon in donkeys (SDFT). Twenty-seven adult donkeys were used in the study. The animals were divided into three equal groups. The 1st group (control group) in which the severed SDFT was sutured without the addition of any adjuvant. In the 2nd group, there was a suture of severed SDFT with the addition of 1ml of 1mM silver nanoparticles (AgNPs group). The 3rd group was subjected to the cutting of SDFT and then the addition of PRF after its suture. Each group of animals was divided into three equal subgroups that were examined after one, two, and three months, respectively. Each group of animals was clinically evaluated by assessing lameness. Gross and microscopic examinations of the healed tendons were performed after 1, 2, and 3 months of surgery. The results revealed that the lameness degree decreased in the PRF and AgNPs groups, in comparison to the control group, especially in the third month after surgery. As well as the lameness decreased significantly after the 3rd month relative to the 1st-month lameness in the AgNPs group. Interestingly, it was found that the PRF and AgNPs enhanced cell alignment and collagen deposition at the site of tendon injury, particularly among third-month subgroups. Therefore, it could be concluded that the PRF and AgNPs are effective materials for enhancing SDFT healing in donkeys.
... 22,23 Various methods such as the use of cross linkers or additives have been used to modify the properties of Co, especially its mechanical weakness. [24][25][26][27] Silk fibroin is a natural biopolymer with high tensile strength, low immunogenicity, and controllable biodegradability, making it a promising biomaterial for tissue engineering applications. 24,28,29 It has also been proven that silk fibroin can improve the mechanical properties and biodegradability of biological materials such as Co. [24][25][26][27] Studies have shown that silk-based films do not show excellent cell growth. ...
... [24][25][26][27] Silk fibroin is a natural biopolymer with high tensile strength, low immunogenicity, and controllable biodegradability, making it a promising biomaterial for tissue engineering applications. 24,28,29 It has also been proven that silk fibroin can improve the mechanical properties and biodegradability of biological materials such as Co. [24][25][26][27] Studies have shown that silk-based films do not show excellent cell growth. Of course, the production of cell sheets such as corneal epithelial cells on silk designs is possible with manipulations such as increasing porosity in the presence of porous agents and various additives such as growth factors. ...
Natural biomaterials are crucial in ocular tissue engineering because they allow cells to proliferate, differentiate, and stratify while maintaining the typical epithelial phenotype. In this study, membranes as dressings were formed from silk fibroin and collagen (Co) extracted from fish skin and then modified with carbodiimide chemical cross linker in different concentrations. The samples were evaluated by different analyses such as structural, physical (optical, swelling, denaturation temperature, degradation), mechanical, and biological (viability, cell adhesion, immunocytochemistry) assays. The results showed that all membranes have excellent transparency, especially with higher silk fibroin content. Increasing the cross linker concentration and the ratio of silk fibroin to Co increased the denaturation temperature and mechanical strength and, conversely, reduced the degradation rate and cell adhesion. The samples did not show a significant difference in toxicity with increasing cross linker and silk fibroin ratio. In general, samples with a low silk fibroin ratio combined with cross linker can provide desirable properties as a membrane for corneal wound healing.
... Common grafts used to reconstruct the ACL in rabbits include PT, ST, and LDE autografts. 18,65,[104][105][106]108,109 However, due to the variation in size, especially cross-sectional area, the mechanical properties of rabbit tendon grafts vary significantly (Table 3). While the PT graft can be harvested similar to human patients, it is not as commonly used as ST and LDE grafts. ...
... 117 Additional imaging techniques, such as µCT scans, have also been implemented in the rabbit model to assess tendon-bone integration. For example, Bi et al. 65 utilized µCT to demonstrate that reconstructing the rabbit ACL with silk-collagen scaffold decreased the average femoral bone tunnel area compared to the semitendinosus autograft at 4 weeks postoperatively. 65 Quantitative computed tomography was used to determine that a 3-week COX-2 inhibitor (celecoxib) treatment decreased area of trabecular bone, cortical density, and new bone formation. ...
... For example, Bi et al. 65 utilized µCT to demonstrate that reconstructing the rabbit ACL with silk-collagen scaffold decreased the average femoral bone tunnel area compared to the semitendinosus autograft at 4 weeks postoperatively. 65 Quantitative computed tomography was used to determine that a 3-week COX-2 inhibitor (celecoxib) treatment decreased area of trabecular bone, cortical density, and new bone formation. 104 Moreover, µCT was also used to evaluate new bone formation between an additive manufactured (AM) porous-titanium interference screw implant and a conventional interference screw. ...
Anterior cruciate ligament (ACL) injuries are common knee ligament injuries. While generally successful, ACL reconstruction that uses a tendon graft to stabilize the knee is still associated with a notable percentage of failures and long‐term morbidities. Preclinical research that uses small laboratory species (i.e., mice, rats, rabbits) to model ACL reconstruction are important to evaluate factors that can impact graft incorporation or post‐traumatic OA after ACL reconstruction. Small animal ACL reconstruction models are also used for proof‐of‐concept studies for development of emerging biologic strategies aimed at improving ACL reconstruction healing. The objective of this review is to provide an overview on the use of common small animal laboratory species to model ACL reconstruction. The review includes a discussion on comparative knee anatomy, technical considerations including types of tendon grafts employed amongst the small laboratory species (i.e., mice rats, rabbits), and common laboratory evaluative methods used to study healing and outcomes after ACL reconstruction in small laboratory animals. The review will also highlight common research questions addressed with small animal models of ACL reconstruction. This article is protected by copyright. All rights reserved.
... molecular weight fiber protein extracted from silk that has appropriate flexibility, tensile strength, moisture permeability and controlled release ability. Many studies have shown that SF hydrogels can stimulate MSCs to differentiate into fibroblasts or osteoblasts and were usually used to repair fibrous tissues such as tendons and bones [40][41][42]. In addition, HA is a high molecular weight polysaccharide composed of two disaccharide units, D-glucuronic acid and N-acetylglucosamine, which has high water retention, viscoelasticity, and biocompatibility. ...
Low back pain is one of the most serious public health problems worldwide and the major clinical manifestation of intervertebral disc degeneration (IVDD). The key pathological change during IVDD is dysfunction of the annulus fibrosus (AF). However, due to the lack of an in-depth understanding of AF biology, the methods to reconstruct the AF are very limited. In this study, the mice AF cell atlas were decoded by single-cell RNA sequencing to provide a guide for AF reconstruction. The results first identify a new population of AF cells, fibrochondrocyte-like AF cells, which synthesize both collagen I and collagen II and are potential functional cells for AF reconstruction. According to the dual features of the AF extracellular matrix, a composite hydrogel based on the acylation of methacrylated silk fibroin with methacrylated hyaluronic acid was produced. To obtain the ability to stimulate differentiation, the composite hydrogels were combined with a fibrochondrocyte-inducing supplement. Finally, reconstruction of the AF defects, by the novel AF stem cell-loaded composite hydrogel, could be observed, its amount of chondroid matrices recovered to 31.7% of AF aera which is significantly higher than that in other control groups. In summary, this study decodes the AF cell atlas, based on which a novel strategy for AF reconstruction is proposed.
