Frontiers in Tissue Engineering

TLDR

Cartilage tissue engineering seeks to create constructs that mimic native articular cartilage in zonal organization, biochemical composition, and mechanical properties for in vitro studies and potential in vivo repair. This review examines how cell seeding density, scaffold design, biochemical signals, mass transport, and culture duration influence chondrogenesis, and outlines essential requirements and research gaps for successful cartilage tissue engineering. The authors expand chondrogenic cells in vitro, seed them onto three‑dimensional polymeric scaffolds, and culture the constructs in bioreactor vessels. Cultivation leads to physiologic cellularity, progressive increases in glycosaminoglycan and Type II collagen, scaffold biodegradation, and construct composition, morphology, and mechanical properties that vary with culture conditions.

Abstract

Cartilage tissue engineering can provide functional cartilaginous constructs that can be used for controlled in vitro studies of chondrogenesis and potentially for in vivo articular cartilage repair. Ideally, engineered cartilage should be indistinguishable from native articular cartilage with respect to zonal organization, biochemical composition, and mechanical properties. In the model system presented here, chondrogenic cells are expanded in vitro as required, seeded onto three-dimensional polymeric scaffolds, and cultured in bioreactor vessels. During the course of in vitro cultivation, construct cellularity plateaus at a physiologic level, fractions of glycosaminoglycan and Type II collagen increase progressively, and the scaffold biodegrades. Construct structure (composition, morphology) and function (biosynthetic activity, mechanical properties) depend on cultivation conditions. This paper reviews recent studies of in vitro modulation of chondrogenesis by: (1) cell seeding density and source; (2) the tissue regeneration template; (3) biochemical regulatory signals; (4) mixing, mass transport and hydrodynamic forces; and (5) cultivation time. Key requirements and some of the critical research needs for successful cartilage tissue engineering are discussed.