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New Scaffolds & Cells
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New Scaffolds & Cells

Numerous surgical procedures have been suggested and tried over many decades to treat damage to joint (‘articular’) cartilage (known as chondral lesions) or cartilage and the underlying bone (osteochondral lesions), with the aim of restoring the tissue as closely as possible to the original cartilage. However, no methods to date have been able to completely match the properties of normal, healthy cartilage.

Scaffolds are temporary 3D biodegradable structures that are placed inside cartilage defects as a result of diseased or damaged cartilage. The scaffolds typically fall into four main types: protein-based scaffolds, carbohydrate-based scaffolds, synthetic or artificial polymer-based scaffolds, and a combination of any of these types. Scaffolds can also be in several forms: membranes, meshes or hydrogels.

Scaffolds should be:

  • Biocompatible, and cause little or no inflammatory response in the body
  • Harmless when broken down by the body
  • Porous enough to allow new cartilage growth and the eventual breakdown of the scaffold, while forming a ‘net’ to maintain the most suitable environment for cartilage repair
  • Easy to produce and versatile, depending on the size and shape required
  • Able to withstand the stresses and forces within the joint (e.g., the knee)

Scaffolds can be implanted as part of a two-step procedure, in which the scaffolds are combined with cartilage cells (chondrocytes) multiplied previously in the laboratory. This is a process similar to that used in autologous chondrocyte implantation (ACI) and is called matrix-assisted autologous chondrocyte transplantation (MACT) or matrix-assisted autologous chondrocyte implantation (MACI).

Alternatively, the scaffolds are implanted in a one-step procedure, in which the scaffold is placed in the defective cartilage either after marrow stimulation (drilling or microfracture) or as a plug that encourages new cartilage growth (known as ‘smart’ scaffolds).

While there is long-term follow-up showing that the previously used scaffolds plus chondrocytes produce good results, longer-term data for the newer ‘smart’ scaffolds is awaited.

The uses, advantages and disadvantages, and clinical evidence for scaffolds in cartilage repair are discussed below.

Intended audience

This article is intended for anyone suffering from damage to their articular cartilage and their families who would like to find out about new scaffolds, as well as anyone interested in cartilage problems.

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New Scaffolds 2 Steps

What are new scaffolds for cartilage repair?

Scaffolds for cartilage regeneration were introduced the late 1990s. These were advanced biopolymers used as a support for cartilage cells taken from the patient, or ‘autologous chondrocytes’.

Similarly to the procedure for ACI, the surgeon first performs (arthroscopy) to harvest small pieces of cartilage containing cartilage cells (chondrocytes), from a non-weight-bearing part of the joint. The cartilage pieces are sent to a laboratory, where the cells are isolated and cultured (multiplied) for 3–5 weeks to obtain sufficient number of cells (usually between 5 and 12 million cells). The chondrocytes are then placed on the scaffold so that they can multiply and mature for one to several days. The scaffold combined with chondrocytes is subsequently transplanted into the damaged or diseased area of the joint.

In parallel, one-step techniques have also become available. For these procedures, an improved, ‘smart’ biomaterial, which is capable of assisting the body’s own “building cells” to form cartilage tissue, is placed inside the cartilage defect. Bone marrow stimulation techniques are often used in conjunction with these scaffolds to allow the body’s own cells to leave the bone marrow and participate in populating the scaffold.

These bone marrow cells migrate into the scaffold, and the scaffold’s goal is to direct cartilage alone or bone and cartilage cells to grow, mature, and build the corresponding tissues. Today, there are scaffold designed for the reconstruction of cartilage only (chondral defects), or of both bone and cartilage (osteochrondral defects).

The differences between MACT, or scaffolds with autologous chondrocytes, and ‘smart’ scaffolds are the presence of cartilage cells, or chondrocytes, and whether one or two surgeries are required.

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