Composite three-dimensional woven scaffolds with interpenetrating network hydrogels to create functional synthetic articular cartilage

Abstract

The development of synthetic biomaterials that possess mechanical properties that mimic those of native tissues remains an important challenge to the field of materials. In particular, articular cartilage is a complex nonlinear, viscoelastic, and anisotropic material that exhibits a very low coefficient of friction, allowing it to withstand millions of cycles of joint loading over decades of wear. Here we show that a three-dimensionally woven fiber scaffold that is infiltrated with an interpenetrating network hydrogel can provide a functional biomaterial that provides the load-bearing and tribological properties of native cartilage. An interpenetrating dual-network "tough-gel" consisting of alginate and polyacrylamide was infused into a porous three-dimensionally woven poly(ε-caprolactone) fiber scaffold, providing a versatile fiber-reinforced composite structure as a potential acellular or cell-based replacement for cartilage repair.

Keywords: 3-D weaving; IPN; Osteoarthritis; interpenetrating network hydrogels; scaffold; synthetic articular cartilage; tissue engineering.

Figure 1

Compressive and frictional properties of IPN hydrogels. PAAm = polyacrylamide, Alg = alginate, Fib = fibrin, Alg/PAAm = alginate/polyacrylamide & Fib/PAAm = fibrin/polyacrylamide) (A) PCL scaffold alone, PCL/Alg/PAAm-IPN composite, cartilage, and Alg/PAAm strain recovery following 10% strain, (B) Stress-strain behavior of the hydrogels during compression, (C) Young’s modulus of the hydrogels calculated from unconfined compression studies. * P < 0.05 for Alg/PAAm vs. PAAm, Alg, Fib and Fib/PAAm. + P < 0.05 for Fib/PAAm vs. PAAm and Fib. (D) Coefficient of friction of the hydrogels determined using a rheometer. * P < 0.05 for Alg vs. Alg/PAAm, Alg, & Fib/PAAm. + P < 0.05 for Fib vs. PAAm, Alg/PAAm and Fib/PAAm.

Figure 2

(A, B) SEM and 3D optical profile of 3D woven PCL scaffold surface. Outlined area in panel A denotes total scanned area in panel B. (C) Cross-sectional image of 3D woven PCL scaffold. (D, E) SEM and 3D optical profile of 3D woven PCL-Alg/PAAm IPN composite surface. Outlined area in panel D denotes total scanned area in panel E. (F) Cross-sectional image of 3D woven PCL-Alg/PAAm IPN composite scaffold. (G, H) SEM and 3D optical profile of Alg/PAAm IPN surface. (I) Average RMS of the 3D woven PCL scaffold (scaffold), Alg/PAAm IPN (hydrogel), and 3D woven PCL-Alg/PAAm IPN composite (composite) constructs. * P < 0.05 for hydrogel vs. scaffold & composite. + P < 0.05 for composite vs. scaffold and hydrogel. All scale bars = 200 µm.

Figure 3

(A) Young’s modulus of the PCL scaffold alone and the IPN hydrogel composites (All groups in this plot contain the PCL scaffold – the hydrogel was infused in the PCL scaffold to create the composite). * P < 0.05 for Alg/PAAm vs. all groups except Fib/PAAm. + P < 0.05 for Fib/PAAm vs. all groups except Alg/PAAm. (B) Aggregate modulus of IPN and single network hydrogels and their combination with the PCL scaffold to form composites. * P < 0.05 for Alg/PAAm composite vs. all groups. + P < 0.05 for Fib/AAM hydrogel vs. all groups. ** P < 0.05 for Fib/PAAm composite vs. Alg and Fib composites and scaffold alone. (C) Stress-strain behavior and (D) dynamic moduli of porcine articular cartilage, Alg/PAAm hydrogel, Alg/PAAm composite and woven scaffold.

Figure 4

The equilibrium coefficient of friction of different constructs tested against native articular cartilage. 3D woven PCL scaffold showed a relatively high coefficient of friction, whereas the Alg/PAAm IPN composite and Alg/PAAm hydrogel showed significantly lower coefficients of friction. * P < 0.05 for 3D woven PCL scaffold vs. hydrogel & composite.