Electrospining Machine: Carbon fiber-mediated electrospinning scaffolds conductively repair tendon defects

Background

Tendons are connective tissues that connect muscle to bone and are an important part of the musculoskeletal system, storing and transferring energy during movement. Tendons consist of bundles of collagen fibers arranged along their longitudinal axis. The regulation of collagen fibers in tendons is complex: it involves the formation of procollagen, collagen protofibrils, collagen fibers, and fascicles. Finally, the tendon matrix consists of fascicles. The collagen fibers have a diameter of 1 ~ 20 μm. however, partial or complete rupture of the tendon due to accidents or excessive exercise can cause alterations in collagen isoform expression and tertiary structure, disrupting the collagenous arrangement and leading to loss of function and reduced mobility.

The main point of this paper

Importance of tendon repair:

Partial or complete rupture of a tendon disrupts the collagen structure, leading to disruption of the electrical signaling pathway, and reestablishment of the original electrical signaling pathway of the tendon is essential to promote regeneration and functional recovery of the defective tendon

Conductive carbon fiber-mediated electrostatically spun scaffold:

Carbon fiber-mediated electrostatically spun scaffolds were fabricated by wrapping electrically conductive, high-strength, loosely packed single bundles of carbon fibers with Nanofiber Membrane. The maximum tensile force of this scaffold was 2.4-fold higher than that of carbon fibers, providing excellent temporal and spatial conditions for tendon cells to adapt to the accelerated proliferation and expression of electrical stimuli

Design and effect of the scaffold:

The carbon fiber monofilaments used in the scaffolds have a diameter of 5.07 ± 1.20 μm, which matches the diameter of tendon collagen, allowing for the rapid establishment of connections between tendon tissues and the scaffolds, and better facilitating the restoration of electrical signaling pathways

Animal model study:

In a rabbit Achilles tendon defect repair model, the carbon-fiber-mediated electrostatically spun scaffolds were nearly filled with collagen fibers and showed better repair results compared with the nonconductive polyethylene terephthalate scaffolds

Transcriptome sequencing results:

Transcriptome sequencing showed that the expression of fiber regulatory protein and tendon regulatory protein was up-regulated, and the proteoglycan and glycosaminoglycan-binding protein pathways associated with them were enhanced, thus regulating the TGF-β signaling pathway, optimizing extracellular matrix assembly, and promoting tendon repair

Carbon fiber-mediated electrostatically spun scaffolds: a new strategy to facilitate tendon defect repair

Tendon injury and electrical signals:

Partial or complete rupture of a tendon disrupts the collagen structure and interrupts electrical signaling pathways, which poses a challenge for regeneration and functional recovery of the tendon.

Scaffold Design and Function:

The carbon-fiber-mediated electrostatically spun scaffolds developed in the study enhanced the maximum tensile force of the scaffolds by wrapping the carbon fibers with Nanofiber Membrane, which increased the maximum tensile force of the scaffolds by 2.4-fold, while providing a suitable environment for cell proliferation and expression.

Matching of scaffolds to tendon collagen:

The diameter of the carbon fiber monofilament used matches the diameter of the tendon collagen, which helps to quickly establish the connection between the tendon tissue and the scaffold, and promotes the recovery of the electrical signaling pathway.

Animal model findings:

In a rabbit Achilles tendon defect repair model, carbon fiber-mediated electrostatically spun scaffolds showed better collagen fiber filling compared to nonconductive polyethylene terephthalate scaffolds.

Transcriptome sequencing analysis:

Transcriptome sequencing showed upregulation of fibronectin and tendonectin expression and enhancement of related pathways, which could regulate the TGF-β signaling pathway, optimize extracellular matrix assembly, and promote tendon repair.

Effect of electrical conductivity on repair:

The study reveals the potential impact of electrical conductivity on tendon repair signaling pathways, providing new avenues for clinical research.

Summarize

In this study, a carbon fiber-mediated electrospun scaffold was designed. The diameter of the reinforcing core CF in this CPS was similar to that of collagen fibers, which could promote the rapid recovery of endogenous electric field disappearing from the defective tendon in vivo.The nanofibrous membrane on the surface of the CPS could help tendon cells to adapt to the ES, and accelerate proliferation and expression. Rabbit Achilles tendon defect test showed that CPS was more favorable for collagen fiber production. It was found by RNA-seq that tendon repair was related to the TGF-β signaling pathway, and CPS upregulated the expression of FMOD and TNMD, which together promoted tendon repair.