Cell Sources for Cartilage Repair-Biological and Clinical Perspective

Abstract

Cell-based therapy represents a promising treatment strategy for cartilage defects. Alone or in combination with scaffolds/biological signals, these strategies open many new avenues for cartilage tissue engineering. However, the choice of the optimal cell source is not that straightforward. Currently, various types of differentiated cells (articular and nasal chondrocytes) and stem cells (mesenchymal stem cells, induced pluripotent stem cells) are being researched to objectively assess their merits and disadvantages with respect to the ability to repair damaged articular cartilage. In this paper, we focus on the different cell types used in cartilage treatment, first from a biological scientist's perspective and then from a clinician's standpoint. We compare and analyze the advantages and disadvantages of these cell types and offer a potential outlook for future research and clinical application.

Keywords: articular cartilage; autologous chondrocyte transplantation; cartilage repair; chondrocytes; regenerative medicine; stem cells; tissue engineering.

Figure 1

Three essential components of new strategies for cartilage treatment: cells, signals, and scaffolds.

Figure 2

Expansion in culture of nasal chondrocytes derived from sheep nasal septum.

Figure 3

The single-step, full-arthroscopic autologous minced cartilage procedure for the treatment of knee cartilage defect. (a) Articular cartilage defect on the medial condyle of the left knee. (b) Defect after the debridement of all unstable cartilage with appropriate steep edges. During this step, chondral fragments are harvested for the preparation of the paste. (c) The arthroscopic fluid is drained from the knee, and the lesion is dried with a cotton swab. (d) Paste mixture containing autologous chondral fragments and platelet-rich plasma (PRP) is carefully placed into the defect. The last step involves the introduction of autologous thrombin serum. The combination of the fibrinogen contained in the paste and the thrombin applied creates a stable clot that holds the mixture in the lesion.

Figure 4

Transplantation of nasal-chondrocyte engineered construct for the treatment of the full-thickness cartilage defect in a 28-year-old athlete [19]. (a) Exposure of the full-thickness cartilage defect of the medial femoral condyle via mini-arthrotomy. (b) Debridement of the cartilage lesion to remove the damaged cartilage and establish adequate shouldering of the lesion. (c) Tissue-engineered cartilage cut to the right shape and ready for implantation. (d) Tissue-engineered cartilage inserted in the cartilage defect and secured by 5–0 monofilament absorbable sutures.

Figure 5

Wet lab mechanical stability testing of the iPSCs-based engineered cartilage construct. (a) Cartilage constructs engineered from iPSCs differentiated into chondrocytes. (b,c) Special drill was used to create defects on sheep trochlea. (d) Full-thickness cartilage defect on sheep trochlea. (e) Cartilage construct ready for press-fit transplantation. (f) Cartilage construct seated in the defect. Stable, no protrusion beyond the defect borders. (Cartilage constructs were grown and provided by Wa’el Kafienah, University of Bristol, U.K.).