A puzzle assembly strategy for fabrication of large engineered cartilage tissue constructs

Abstract

Engineering of large articular cartilage tissue constructs remains a challenge as tissue growth is limited by nutrient diffusion. Here, a novel strategy is investigated, generating large constructs through the assembly of individually cultured, interlocking, smaller puzzle-shaped subunits. These constructs can be engineered consistently with more desirable mechanical and biochemical properties than larger constructs (~4-fold greater Young's modulus). A failure testing technique was developed to evaluate the physiologic functionality of constructs, which were cultured as individual subunits for 28 days, then assembled and cultured for an additional 21-35 days. Assembled puzzle constructs withstood large deformations (40-50% compressive strain) prior to failure. Their ability to withstand physiologic loads may be enhanced by increases in subunit strength and assembled culture time. A nude mouse model was utilized to show biocompatibility and fusion of assembled puzzle pieces in vivo. Overall, the technique offers a novel, effective approach to scaling up engineered tissues and may be combined with other techniques and/or applied to the engineering of other tissues. Future studies will aim to optimize this system in an effort to engineer and integrate robust subunits to fill large defects.

Cell-laden hydrogels for osteochondral and cartilage tissue engineering

“…A novel 3D puzzle assembling technology was developed recently to manufacture engineered large-scale cartilage tissue constructs of agarose hydrogels with improved mechanical and biochemical properties (Fig. 6C) [286]. The constructs were composed of individually cultured, chondrocyte-laden interlocking smaller puzzle-shaped subunits.…”

Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

“…The need to create a shape-specific construct can be obviated by using multiple, small constructs to create a larger construct in situ . This strategy is used by Chondrosphere ® and others (253, 254). Stiffer constructs, such as Cartipatch ® , RevaFlex ™ , and INSTRUCT are less able to conform to the defect shape and may require the proper shape to be engineered into the implant.…”

Nutrient Channels Aid the Growth of Articular Surface-Sized Engineered Cartilage Constructs

“…67 Although we did not measure failure properties in the current study, we have thusly characterized chondrocyte-seeded agarose constructs in previous work. 34,68 As we further improve culture conditions in this model system, we expect to characterize failure properties systematically before in vivo implantation of constructs.…”

“…32 Using small constructs to repair large defects would require a mosaicplastylike procedure, which may suffer from poor integration. [32][33][34] The addition of channels reduces transport distances, mitigating diffusional limitations and improving mechanical properties of the constructs. 10,35 In our recent studies, the combination of suspension culture and sufficient glucose supply permitted Ø10 mm constructs with 3 or 12 evenlyspaced Ø1 mm channels (CH3 or CH12, respectively) to attain functional properties on par with those of Ø4 mm constructs, including native E Y and GAG content.…”

“…Thus, other studies have used passaged bovine, canine, or human chondrocytes. 34,[41][42][43][44][45][46][47][48][49] A direct comparison of passaged versus primary bovine chondrocytes in agarose could elucidate whether results derived with primary bovine cells are applicable for passaged cells.…”