Table 4.

Natural scaffolds approved for medical use for cartilage tissue engineering.

Product (Company)	Materials	Characteristic
Hyalofast®(Anika) [110,154,174,175]	Benzyl ester of hyaluronic acid	A bioresorbable3D scaffold used through a one-step procedure aftera microfracture. It can be used even for deep cartilage lesions. The scaffold’s non-woven structure allows it to be cut and adaptively matched into uneven lesions.
NeoCart®(Histogenics) [44,110,154]	Bovine type I collagen	Bioresorbableelectrospun scaffold used in MACI, a two-step procedure. The patient’s chondrocytes are expanded into scaffolds. Then, they are incubated in the Tissue Engineering Processor (TEP), which simulates the variation of mechanical forces and reduces oxygen pressure, allowing the maintenance of the chondrocyte phenotype forming the appropriate proteins of the ECM.
ChondroGide(Geistlich) [110,154]	Type I/III collagen	The first described matrix for the ACI method. It is used in a one-step procedure. ChondroGide’s role is to support and promote the chondrogenic differentiation of MSCs released after the microfracture method.
ACI-MaixTM (MACI) [44,45]	Type I/III collagen	The procedure is a two-step process. Expanded autologous chondrocytes (2 or 3 passage) are cultured into the scaffold for 3 or 4 days before implantation into the patient.
Cartipatch®(Xizia Biotech) [44,156,173]	Agarose and alginate	The cylindrical scaffold of a single layer of hydrogel with expanded cartilage cells. The clinical procedure is the same as that for the two-step method. The alginate polymer provides elasticity to the matrix, which facilitates handling during the surgical procedure.
NOVOCART® 3D—AesculapOrthopaedics (BBraun) [44,64,111,156]	Type I collagen, chondroitin sulfate	A sponge scaffold with a bilayer structure and interconnected pores, used in a two-step procedure. This scaffold is desirable in young patients,<16 years old, to avoid eventual secondary injuries, such as early osteoarthritis.
CaReS®(Arthrokinetics) [44,64,111,156]	Type I collagen gel	The scaffold is used in a two-step clinical procedure. Isolated autologous chondrocytes are mixed with a fluid matrix. Then, after 14 days, it is set in the lesion using fibrin glue. The height, thickness, and size of the hydrogel can be easily adjusted to the lesion.
CARTISTEM® (Medipost) [49,176,177]	Hyaluronic acid	Allogeneic human umbilical cord blood (hUCB)-derived MSCs and HA hydrogel products for cartilage regeneration for repeated traumas or degenerative osteoarthritis. A 7-year follow-up study of 104 patients showed promising efficacy in terms of durable cartilage regeneration with no significant adverse effects.