Cell manufacturing for clinical applications.

Abstract

The study of adipose tissue derived mesenchy-mal stem cells (AD-MSCs) injection for osteoar-thritis by Jo et al. [1] was fascinating to us. It is apromising study with good clinical trial designthat contains valuable clinical information. Incontrast to clinical data, cell manufacturing pro-cess has been briefly described. As persons whoare interested in clinical grade cell manufactur-ing, we read the article, cited references, and theauthors’ previous publications to find out moredetails of their cell processing method. Our find-ings suggested that the cell manufacturing is notfully cGMP (current Good Manufacturing Prac-tice) compatible and needs to be improved.According to current regulations, cell-basedproducts should be manufactured under princi-ples ofcGMP when theyare used in clinical stud-ies. Besides cGMP facility (GMP condition), it isrecommended to use FDA-approved or cleared,cGMP manufactured, or clinical grade reagentswhenever they are available. If a research gradereagent is used as part of the manufacturing pro-cess, additional testing may be needed to ensurethe safety and quality of the reagent [2]. Clinicalgrade cell manufacturing cannot be achieved bytransfer of current methodology into a cleanroom [3].The Authors applied collagenase type Ifor tissue digestion that seems to be researchgrade and its manufacturer is unclear. Collage-nase may contain mammalian-based compo-nents that may carry infectious agents such asprions. Other types of collagenase such as:CLSAFA (Worthington, Lakewood, NJ, http://www.worthington-biochem.com), NB 6 GMPgrade (Serva, Heidelberg, Germany, http://www.serva.de), and Liberase MTF-S GMP grade (RocheDiagnostics, Basel, Switzerland, http://www.roche-applied-science.com) have been used foradipose tissue digestion. These clinical-gradeproducts can replace current research-grade col-lagenase without any negative effect in the yieldor function of AD-MSCs [4]. The authors statedthat fetal bovine sera (FBS) obtained from bovinespongiform encephalopathy free herd. However,the manufacturer of FBS, virus inactivationmethod (e.g., gamma irradiation), and its countryof origin are unclear. If animal products cannotbe replaced, we should use materials that aresourced in a controlled and documented mannerfrom animals bred and raised in captivity incountries or geographic regions with appropriatenational health status, disease prevention, andcontrol systems [3].The European Directorate forthe Quality of Medicine & Healthcare hasprovided a list of Transmissible SpongiformEncephalopathies certified sera in its website [5].We also could not find details of their passagingprotocol. In clinical grade cell manufacturing,porcine trypsin should be replaced by animalorigin-free alternatives such as: TrypLE Select(Invitrogen, Carlsbad, CA, http://www.invitrogen.com) and TrypZean (Sigma-Aldrich, St. Louis, MO,http://www.sigmaaldrich.com). These reagentshave been successfully used for passaging AD-MSCs and are gentle on cells [6]. To propagateAD-MSCs, rEGF (Recombinant EpidermalGrowth Factor) supplemented keratinocyte-SFM medium has been used in the study.Although rEGF and bFGF (Basic FibroblastGrowth Factor) accelerate AD-MSC expansionand conserve the spindle shape morphology, itmay limit its differentiation ability during exvivo expansion. Therefore, these growth factorsshould be carefully considered in stem cellsfor clinical applications [7]. Furthermore, K lleet al. have described a simple, growth factor-free GMP compatible protocol which yieldedan average of 8.58 3 10