The Up-Scale Manufacture of Chondrocytes for Allogeneic Cartilage Therapies.

BACKGROUND: Allogeneic chondrocyte therapies need to be developed to allow more individuals to be treated with a cell therapy for cartilage repair and to reduce the burden and cost of current two-stage autologous procedures. Up-scale manufacture of chondrocytes using a bioreactor could help provide an off-the-shelf allogeneic chondrocyte therapy with many doses being produced in a single manufacturing run. Here we assess a Good Manufacturing Practice compliant hollow-fibre bioreactor (Quantum®) for adult chondrocyte manufacture.

METHODS: Chondrocytes were isolated from knee arthroplasty derived cartilage (n=5) and expanded in media supplemented with 10% fetal bovine serum (FBS) or 5% human platelet lysate (hPL) on tissue culture plastic (TCP) for a single passage. hPL supplemented cultures were then expanded in the Quantum® bioreactor for a further passage. Matched, parallel cultures in hPL or FBS were maintained on TCP. Chondrocytes from all culture conditions were characterised in terms of growth kinetics, morphology, immunoprofile, chondrogenic potential (chondrocyte pellet assays) and single telomere length analysis.

RESULTS: Quantum® expansion of chondrocytes resulted in 86.4±38.5x106 cells in 8.4±1.5 days, following seeding of 10.2±3.6 x106 cells. This related to 3.0±1.0 population doublings in the Quantum® bioreactor, compared with 2.1±0.6 and 1.3±1.0 on TCP in hPL and FBS supplemented media, respectively. Quantum® and TCP expanded cultures retained equivalent chondropotency and mesenchymal stromal cell markers immunoprofiles, with only integrin marker, CD49a, decreasing following Quantum® expansion. Quantum® expanded chondrocytes demonstrated equivalent chondrogenic potential (as assessed by ability to form and maintain chondrogenic pellets) with matched hPL TCP populations. hPL manufacture however, led to reduced chondrogenic potential and increased cell surface positivity of integrins CD49b, CD49c and CD51/61 compared with FBS cultures. Quantum® expansion of chondrocytes did not result in shortened 17p telomere length when compared with matched TCP cultures.

DISCUSSION: This study demonstrates that large numbers of adult chondrocytes can be manufactured in the Quantum® hollow-fibre bioreactor. This rapid, up-scale expansion, does not alter chondrocyte phenotype when compared with matched TCP expansion. Therefore, the Quantum® provides an attractive method of manufacturing chondrocytes for clinical use. Media supplementation with hPL for chondrocyte expansion may, however, be unfavourable in terms of retaining chondrogenic capacity.