Hyaline-like tissue seen in defects treated with stem cells and platelet rich plasma

Analysis showed a higher relation between Collagen I and II after stem cell treatments.

By Gina Brockenbrough
ORTHOPEDICS TODAY 2009; 29:28

MIAMI — Treating chondral defects with mesenchymal stem cells delivered in a scaffold with platelet-rich plasma may result in repair tissue with properties more similar to normal hyaline cartilage than the repair tissue seen in controls, the use of scaffolds alone or loading scaffolds with stem cells alone.

“The treatment of full-thickness chondral defects with a collagen scaffold, mesenchymal stem cells compromised to the chondrocyte lineage and platelet rich plasma shows promising results,” Alex Vaisman, MD, said during his presentation at the 8th World Congress of the International Cartilage Repair Society. “Nevertheless, none of the treatment groups healed with normal hyaline cartilage.”

To evaluate the properties of repair tissue created after treating full-thickness chondral defects of the knee with a bi-layer collagen scaffold embedded with autologous mesenchymal stem cells (MSCs) induced to chondrocyte differentiation and platelet-rich plasma (PRP), Vaisman and his colleagues created 20 mm² acute full-thickness chondral defects in 36 femoral condyles of adult male New Zealand White rabbits.

They randomly assigned the rabbits to the following four groups:

• Group 1 in which the lesion was left untreated;
• Group 2 in which surgeons implanted a scaffold without MSCs or PRP;
• Group 3 in which a scaffold containing MSCs was implanted; and
• Group 4 in which a scaffold contained MSCs and PRP.

The investigators sacrificed the rabbits after 6 months. They evaluated the femoral condyles macroscopically, histologically using hematoxylin-eosin and Toluidine Blue staining, and molecularly using quantitative real-time polymerase chain reaction of Collagen II/I and aggrecan/versican.

Evaluation

A rabbit knee with a scaffold containing mesenchymal stem cells and platelet-rich plasma. Image: Vaisman A

Using macroscopy, the investigators discovered fibrous tissue without bony exposure in the control group.

“Groups 2 and 3 showed a hypertrophic, soft, irregular tissue covering the whole lesion,” Vaisman said. “Group 4 has similar- to normal-hyaline cartilage.”

Histology revealed that all of the groups had some fibrocartilage, but the investigators found no significant difference among the groups.

“However, groups 3 and 4 had a slightly more similar appearance to hyaline cartilage than the other groups,” Vaisman said.

Upon molecular analysis, the investigators discovered that groups 3 and 4 had a significantly higher relation between Collagen II and I compared to the other groups.

Alan J. Nixon, MD, a co-moderator of the session, noted that PRP can contain a variety of growth factors. “Do you know what you used for PRP?” Nixon asked. “Did you assay what factors were in that?”

Vaisman said that the investigators did not assess which growth factors were in the PRP or determine the concentrations of these growth factors.

For more information:

• Alan J. Nixon, MD, can be reached at Cornell University, College of Veterinary Medicine, C3-187 VMC, Ithaca, NY 14853; 607-253-3224; e-mail: ajn1@cornell.edu.
• Alex Vaisman, MD, can be reached at Orthopaedic Surgery Unit, Clínica Alemana de Santiago, and Faculty of Medicine, Universidad del Desarrollo, P.O. Box 3737, Santiago, Chile; (56-2) 210-11 11, 212-97 00; e-mail: avaisman@alemana.cl. They have no direct financial interest in any companies or products mentioned in this article.

Reference:

• Vaisman A, Figueroa D, Calvo R, et al. Treatment of full-thickness chondral defects with a collagen scaffold, mesenchymal stem cells compromised to the chondrocyte lineage and platelet rich plasma. Paper #9.2.7. Presented at the 8th World Congress of the International Cartilage Repair Society. May 23-26, 2009. Miami.