What did the study look at?
The authors note that autologous chondrocyte implantation (growing and implanting the patient's own cartilage cells) for joint cartilage damage has the disadvantage of requiring two stages and open surgery. The aim of the study was to develop a less invasive tissue-engineering method using microspheres (tiny gel beads) that carry cartilage cells and are coated with antibodies so that they target the damaged area.
How was it done?
- In the laboratory, mesenchymal stem cells were obtained from the sheep's fat tissue and turned into cartilage cells.
- The cells were placed in alginate microspheres about 500 micrometres across; the spheres were coated with a chitosan polymer and antibodies were attached to their surface.
- Twenty-eight female Akkaraman sheep aged 20-22 months were randomly divided into four groups of 7: untreated control, microfracture (small holes in the bone to stimulate the marrow), cell-seeded scaffold and microsphere injection.
- A defect 8 mm wide and 5 mm deep was created in the right knee of every animal.
- After 3 months the knees were assessed with 3 Tesla MRI, visual (macroscopic) inspection and examination of tissue under the microscope.
What did it find?
- In the laboratory, the viability of encapsulated cells was 62.23 ± 3.02 before targeting and 68.92 ± 3.37 in the targeted microspheres (with unencapsulated cells taken as 100).
- The mean MRI cartilage repair score (MOCART, maximum 100) was 11.86 in the control group, 32.71 with microfracture, 36.43 with the scaffold and 52.71 with microspheres. The microsphere group differed significantly from the microfracture (p = 0.004) and scaffold (p = 0.015) groups; there was no significant difference between microfracture and scaffold.
- Visual assessment scores (ICRS) were 2.7 for control, 6.6 for microfracture, 8.3 for the scaffold and 9.1 for microspheres.
- Under the microscope, scar tissue was seen in the control group and fibrous cartilage in the microfracture group; hyaline-like cartilage formed in the scaffold and microsphere groups, more markedly in the microsphere group.
The authors' conclusion
The authors believe that bio-targeted microspheres may be a more effective, easier and safer approach for cartilage tissue engineering than previous alternatives. They note that the scaffold and microsphere results were similar, but that the methods of application (open surgery versus injection) differ.
Limitations
According to the authors, the study does not show how the microspheres move within the joint and reach the target, or whether they interact with other tissues. Only one microsphere/polymer ratio was tested, and the 3-month follow-up may have been too short to show hyaline cartilage formation. Two authors also declared a competing interest owing to a pending patent application on the technique.
Reference
Bozkurt M, Aşık MD, Gürsoy S, Türk M, Karahan S, Gümüşkaya B, Akkaya M, Şimşek ME, Cay N, Doğan M. (2019). Autologous stem cell-derived chondrocyte implantation with bio-targeted microspheres for the treatment of osteochondral defects. Journal of Orthopaedic Surgery and Research, 14, 394. Licence: CC BY 4.0.
DOI: 10.1186/s13018-019-1434-0
Free full text: PMC6883666
This article summarises a published scientific paper for general information; it does not replace an examination or a personal medical assessment. Please consult your doctor about your symptoms.
