Biomaterials for the Treatment of Tendon Injury

Abstract

Background: Most tendon injuries are occurring from a gradual wearing and tearing of the tendon tissues from overuse. Such injuries are usually seen in sports, exercising, or daily activities that involve a high mechanical load and weight bearing. However, owing to the lack of both cellularity and blood vessels in tendons, the process of tendon repair is slow and inefficient. Although various conservative (non-surgical) and surgical management options are conducted by the clinicians, a gold standard of these approaches does not exist. In this regard, the treatment of tendon injuries is challenging.

Method: Here, we describe the recent advances of biomaterial-based approaches for the treatment of injured tendons.

Results: Regenerative medicine is an emerging multidisciplinary research that specializes in the repair of damaged tendon tissues through the delivery of regenerative factors by biomaterials.

Conclusion: Although current biomaterial-based treatment strategies have shown their potential for tendon healing, future research and clinical applications should focused on finding the optimum combinations of regenerative factors with ideal biomaterials for the repair of tendons.

Keywords: Biomaterials; Blood vessel; Delivery; Regenerative factor; Tendon healing.

Fig. 1

Biological treatment approaches for tendon repair using injectable therapeutics containing platelet-rich plasma, cells, proteins, or genes

Fig. 2

Magnetic resonance imaging T2-weighted images at 4 weeks after treatment. Transverse images of the treated tendon in the A saline, B Lr-PRP, C Lp-PRP, and D normal groups. Adapted from [25]. Red arrow means increased signal that indicates inflammatory edema

Fig. 3

Representative bioluminescence image. Hydrogel + PRP + ASCs increased cell proliferation and survival in comparison to Hydrogel + ASCs. POD means post-operative day. Adapted from [72]. Scale bar means the biomuminescence signal intensity; red: high and blue: low

Fig. 4

Local intratendinous injection of drug-loaded porous microspheres into a rat model of collagenase-induced tendinopathy. Collagenase injection into the tendon tissue increased the mRNA levels of the pro-inflammatory cytokines [matrix metalloproteinase (MMP)-3, MMP-13, cyclooxygenase-2 (COX-2), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α)]. The increased pro-inflammatory cytokines induced collagen fiber disruption, resulting in decreased tensile strength. The local intratendinous injection of drug-loaded porous microspheres significantly reduced these pro-inflammatory cytokines, repairing the collagen fiber organization and tensile strength and leading to restoration of the tendon tissues

Fig. 5

Color Doppler ultrasound of low (50 μg), mid (250 μg) and high (500 μg) dose anti-VEGF antibogy (B20) at days 7 and 14. Adapted from [86]. Color Doppler means the flow of blood based on its direction of flow; red towards to top of the transducer, blue away from the transducer. Red–orange and blue–sky blue indicate the different velocities of blood flow