Scaffold-Based or Scaffold-Free Bioprinting: Competing or Complementing Approaches?

Bioprinting is an emerging technology to fabricate artificial tissues and organs through additive manufacturing of living cells in a tissues-specific pattern by stacking them layer by layer. Two major approaches have been proposed in the literature: bioprinting cells in a scaffold matrix to support cell proliferation and growth, and bioprinting cells without using a scaffold structure. Despite great progress, particularly in scaffold-based approaches along with recent significant attempts, printing large-scale tissues and organs is still elusive. This paper demonstrates recent significant attempts in scaffold-based and scaffold-free tissue printing approaches, discusses the advantages and limitations of both approaches, and presents a conceptual framework for bioprinting of scale-up tissue by complementing the benefits of these approaches.