The
development of suitable synthetic scaffolds for use as human
tendon grafts to repair tendon ruptures remains a significant engineering
challenge. Previous synthetic tendon grafts have demonstrated suboptimal
tissue ingrowth and synovitis due to wear particles from fiber-to-fiber
abrasion. In this study, we present a novel fiber-reinforced hydrogel
(FRH) that mimics the hierarchical structure of the native human tendon
for synthetic tendon graft material. Ultrahigh molecular weight polyethylene
(UHMWPE) fibers were impregnated with either biosynthetic polyvinyl
alcohol/gelatin hydrogel (FRH-PG) or with polyvinyl alcohol/gelatin
+ strontium-hardystonite (Sr-Ca2ZnSi2O7, Sr-HT) composite hydrogel (FRH-PGS). The scaffolds were fabricated
and assessed to evaluate their suitability for tendon graft applications.
The microstructure of both FRH-PG and FRH-PGS showed successful impregnation
of the hydrogel component, and the tendon scaffolds exhibited equilibrium
water content of ∼70 wt %, similar to the values reported for
native human tendon, compared to ∼50 wt % water content retained
in unmodified UHMWPE fibers. The tensile strength of FRH-PG and FRH-PGS
(77.0–81.8 MPa) matched the range of human Achilles’
tendon tensile strengths reported in the literature. In vitro culture
of rat tendon stem cells showed cell and tissue infiltration into
both FRH-PG and FRH-PGS after 2 weeks, and the presence of Sr-HT ceramic
particles influenced the expression of tenogenic markers. On the other
hand, FRH-PG supported the proliferation of murine C2C12 myoblasts,
whereas FRH-PGS seemingly did not support it under static culture
conditions. In vivo implantation of FRH-PG and FRH-PGS scaffolds into
full-thickness rat patellar tendon defects showed good collagenous
tissue ingrowth into these scaffolds after 6 weeks. This study demonstrates
the potential viability for our FRH-PG and FRH-PGS scaffolds to be
used for off-the-shelf biosynthetic tendon graft material.