Title: Impact of human platelet lysate on the expansion and chondrogenic capacity of cultured human chondrocytes for cartilage cell therapy

Authors: JG Sykes, JH Kuiper, JB Richardson, S Roberts, KT Wright, NJ Kuiper

Address: Institute of Science and Technology in Medicine (ISTM), University of Keele, Arthritis Research Centre, The Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire, SY10 7AG, UK.

E-mail: n.j.kuiper at keele.ac.uk

Abstract: High hopes have been pinned on regenerative medicine strategies in order to prevent the progression of cartilage damage to osteoarthritis, particularly by autologous chondrocyte implantation (ACI). The loss of chondrocyte phenotype during in vitro monolayer expansion, a necessary step to obtain sufficient cell numbers, may be a key limitation in ACI. In this study, it was determined whether a shorter monolayer expansion approach could improve chondrogenic differentiation. The effects of two supplement types, foetal bovine serum (FBS) and Stemulate™ (a commercial source of human platelet lysate), on the expansion and re-differentiation potential of human chondrocytes, isolated from five individuals, were compared. Chondrocytes were expanded with 10 % FBS or 10 % Stemulate™. Pellets were cultured for 28 d in chondrogenic differentiation medium and assessed for the presence of cartilage matrix molecules and genes associated with chondrogenicity. Stemulate™ significantly enhanced the proliferation rate [average population doubling times: FBS, 25.07 ± 6.98 d (standard error of the mean, SEM) vs. Stemulate™, 13.10 ± 2.57 d (SEM)]. Sulphated glycosaminoglycans (sGAG), total collagen and qRT-PCR analyses of cartilage genes showed that FBS-expanded chondrocytes demonstrated significantly better chondrogenic capacity than Stemulate™-expanded chondrocytes. Histologically, FBS-expanded chondrocyte pellets appeared to be more stable, with a more intense staining for toluidine blue, indicating a greater chondrogenic capacity. Although Stemulate™ positively influenced chondrocyte proliferation, it had a negative effect on chondrogenic differentiation potential. This suggested that, in the treatment of cartilage defects, Stemulate™ might not be the ideal supplement for expanding chondrocytes (which maintained a chondrocyte phenotype) and, hence, for cell therapies (including ACI).

Key Words: Human platelet lysate, Stemulate™, foetal bovine serum, human chondrocytes, cartilage, autologous chondrocyte implantation

Publication date: May 2nd 2018

Article download: Pages 255-267
DOI: 10.22203/eCM.v035a18

James died suddenly on 18th February 2018, aged 62, whilst on holiday in India with his wife. James was highly regarded in the orthopaedic and research fields and this has been clearly reflected by the swell of clinicians and scientists from all over the world sending their condolences and thoughts to his family and friends. This has been a huge comfort to them.
James qualified in Medicine with a Commendation in Surgery in 1977. During his long and illustrious career James worked in his native Inverness, Nepal, India, Malawi, Glasgow, Oxford, Leicester and Oswestry. In Oxford he undertook a year of full-time research into fracture healing, completing his MD thesis. During this time, his knowledge in fracture care increased and his focus moved more into clinical research. At Leicester and Oswestry, he was always able to find time for his research interests and he focussed them on the treatment of patients with slow healing fractures or arthritis.In 1994 and at the age of 38, James became Professor of Orthopaedics at the University of Keele and the Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry. James realised that to make progress, he needed to work with and interact with like-minded scientists.