Artificial cartilage
Lastly, in the case of creating synthetic cartilage to be used in joint spaces, high mechanical strength under compression needs to be an intrinsic property of the material.
[3] Each type of cartilage has varying concentrations of components such as proteoglycans, collagen and water which determine its functional properties and location in the body.
Similarly, collagen fibers are aligned perpendicular to the surface in the deep zone in order to restrict compressive forces.
[12] When damage and degradation occurs to the articular cartilage, it can no longer withstand the large loads without pain and discomfort of the individual due to the decrease in mechanical properties.
Many biological agents and chemical compounds have been used in order to prevent matrix-degrading enzymes that actively work to degrade cartilage.
Studies have shown that treatment with NF-κB pathway inhibitor BAY11-7082 restores IL-1b-inhibited chondrogenesis of cartilage stem cells and in turn postpones progression of OA.
Similarly, ample research shows that combined blockade of TNFa and IL-17 with bispecific antibodies reveals an inhibition of both cytokines for reduced cartilage degradation and proinflammatory responses.
Lying self-assembled MSCs (mesenchymal stem cells) on top of chondrocyte-laden hydrogel scaffolds has shown cell-mediated regeneration of hyaline-like cartilage.
However, one drawback of this is that implantation of these scaffolds requires open-joint surgery to gather donor chondrocytes from non-weight-bearing joint cartilage areas.
One study discussed that the 3D woven fibers provide load bearing tribological properties of native cartilage where they are trying to achieve a near frictionless environment.
They are ionically crosslinked networks with a special type of IPN that is capable of scattering mechanical energy while maintaining the shape of a hydrogel after deformation.
However, when using bacterial cellulose and gelatin, it showed a decrease of ultimate stress and it did not meet the requirements of artificial cartilage.
[17] PVA hydrogels prepared by several freezing-thawing, without an externally added crosslinking agent, have also exhibited great promises in terms of biocompatibility, wear resistance, shock absorption, friction coefficient, flexibility, and lubrication (due to uptake/excretion of body fluid).
[1] A two-year implantation of the PVA gels as artificial meniscus in rabbits showed that they remain intact without degradation, fracture, or loss of properties.
When used as a blend of PVA/PVP hydrogel, they produced similar internal 3D structure and water content as natural articular cartilage.
[20] The implant is made of saline and a bio-compatible polymer, and is inserted through an incision between the metatarsophalangeal (MTP) joint where natural cartilage has worn away.
[20] A separate orthopedic implant consisting of a hydrated, interpenetrating dual polymer network based on polyether urethane (PEU) was given breakthrough device designation from the U.S. Food and Drug Administration in July 2021.
[23] Additionally, growth factors have been thoroughly evaluated; however, specific combinations still need to be studied further in order to more effectively generate a tissue that can mimic the properties of natural cartilage.
[25] In September 2021, researchers created cartilage repair implants utilizing a process of three-dimensional weaving to combine artificial materials with stem cells.
[26][27] The bioartificial implants are designed to partly dissolve over time, leaving only natural tissues in the repaired joints.
[26][27] As of October 2021, scientists have seen success in treating dogs but further research is required before the technique could move to clinical trials for humans.
