New concept for a regenerative and resorbable prosthesis for tendon and ligament: physicochemical and biological characterization of PLA-braided biomaterial

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.

Fused Deposition Modeling Printed PLA/Nano β-TCP Composite Bone Tissue Engineering Scaffolds for Promoting Osteogenic Induction Function

Purpose

Large bone defects caused by congenital defects, infections, degenerative diseases, trauma, and tumors often require personalized shapes and rapid reconstruction of the bone tissue. Three-dimensional (3D)-printed bone tissue engineering scaffolds exhibit promising application potential. Fused deposition modeling (FDM) technology can flexibly select and prepare printed biomaterials and design and fabricate bionic microstructures to promote personalized large bone defect repair. FDM-3D printing technology was used to prepare polylactic acid (PLA)/nano β-tricalcium phosphate (TCP) composite bone tissue engineering scaffolds in this study. The ability of the bone-tissue-engineered scaffold to repair bone defects was evaluated in vivo and in vitro.

Methods

PLA/nano-TCP composite bone tissue engineering scaffolds were prepared using FDM-3D printing technology. The characterization data of the scaffolds were obtained using relevant detection methods. The physical and chemical properties, biocompatibility, and in vitro osteogenic capacity of the scaffolds were investigated, and their bone repair capacity was evaluated using an in vivo animal model of rabbit femur bone defects.

Results

The FDM-printed PLA/nano β-TCP composite scaffolds exhibited good personalized porosity and shape, and their osteogenic ability, biocompatibility, and bone repair ability in vivo were superior to those of pure PLA. The merits of biodegradable PLA and bioactive nano β-TCP ceramics were combined to improve the overall biological performance of the composites.

Conclusion

The FDM-printed PLA/nano-β-TCP composite scaffold with a ratio of 7:3 exhibited good personalized porosity and shape, as well as good osteogenic ability, biocompatibility, and bone repair ability. This study provides a promising strategy for treating large bone defects.

Advanced Gene Therapy Strategies for the Repair of ACL Injuries

The anterior cruciate ligament (ACL), the principal ligament for stabilization of the knee, is highly predisposed to injury in the human population. As a result of its poor intrinsic healing capacities, surgical intervention is generally necessary to repair ACL lesions, yet the outcomes are never fully satisfactory in terms of long-lasting, complete, and safe repair. Gene therapy, based on the transfer of therapeutic genetic sequences via a gene vector, is a potent tool to durably and adeptly enhance the processes of ACL repair and has been reported for its workability in various experimental models relevant to ACL injuries in vitro, in situ, and in vivo. As critical hurdles to the effective and safe translation of gene therapy for clinical applications still remain, including physiological barriers and host immune responses, biomaterial-guided gene therapy inspired by drug delivery systems has been further developed to protect and improve the classical procedures of gene transfer in the future treatment of ACL injuries in patients, as critically presented here.

A dual-phase scaffold produced by rotary jet spinning and electrospinning for tendon tissue engineering

Tendon is a highly hierarchical and oriented tissue that provides high mechanical strength. Tendon injuries lead to loss of function, disability, and a decrease in quality of life. The limited healing capacity of tendon tissue leads to scar tissue formation, which can affect mechanical strength and cause a re-tear. Tissue engineering can be the solution to achieving complete and proper healing of tendon. The developed constructs should be mechanically strong while maintaining a suitable environment for cell proliferation. In this study, a dual-phase fibrous scaffold was produced by combining fibrous mats produced by rotary jet spinning (RJS) and wet electrospinning (WES), with the intent of improving the healing capacity of the construct. Dual-phase scaffolds were formed from aligned poly(ϵ-caprolactone) (PCL) fibers (Shell) produced by RJS and randomly oriented PCL or PCL/gelatin fibers (Core) produced by WES systems. The scaffolds mimicked i) the repair phase of tendon healing, in which randomly-oriented collagen type III is deposited by randomly-oriented WES fibers and ii) the remodeling stage, in which aligned collagen type I fibers are deposited by aligned RJS fibers. In vitro studies showed that the presence of randomly-oriented core fibers inside the aligned PCL fiber shell of the dual-phase scaffold increased the initial attachment and viability of cells. Scanning electron microscopy and confocal microscopy analysis showed that the presence of aligned RJS fibers supported the elongation of cells through aligned fibers which improves tendon tissue healing by guiding oriented cell proliferation and extracellular matrix deposition. Tenogenic differentiation of human adipose-derived mesenchymal stem cells on scaffolds was studied when supplemented with growth differentiation factor 5 (GDF-5). GDF-5 treatment improved the viability, collagen type III deposition and scaffold penetration of human adipose derived stem cells. The developed FSPCL/ESPCL-Gel 3:1 scaffold (FS = centrifugal force spinning/RJS, ES = wet electrospinning, Gel = gelatin) sustained high mechanical strength, and improved cell viability and orientation while supporting tenogenic differentiation.

Current Progress in Tendon and Ligament Tissue Engineering

Background

Tendon and ligament injuries accounted for 30% of all musculoskeletal consultations with 4 million new incidences worldwide each year and thus imposed a significant burden to the society and the economy. Damaged tendon and ligament can severely affect the normal body movement and might lead to many complications if not treated promptly and adequately. Current conventional treatment through surgical repair and tissue graft are ineffective with a high rate of recurrence.

Methods

In this review, we first discussed the anatomy, physiology and pathophysiology of tendon and ligament injuries and its current treatment. Secondly, we explored the current role of tendon and ligament tissue engineering, describing its recent advances. After that, we also described stem cell and cell secreted product approaches in tendon and ligament injuries. Lastly, we examined the role of the bioreactor and mechanical loading in in vitro maturation of engineered tendon and ligament.

Results

Tissue engineering offers various alternative ways of treatment from biological tissue constructs to stem cell therapy and cell secreted products. Bioreactor with mechanical stimulation is instrumental in preparing mature engineered tendon and ligament substitutes in vitro.

Conclusions

Tissue engineering showed great promise in replacing the damaged tendon and ligament. However, more study is needed to develop ideal engineered tendon and ligament.