Pathogen-free, plasma-poor platelet lysate and expansion of human mesenchymal stem cells.

BACKGROUND: Supplements to support clinical-grade cultures of mesenchymal stem cells (MSC) are required to promote growth and expansion of these cells. Platelet lysate (PL) is a human blood component which may replace animal serum in MSC cultures being rich in various growth factors. Here, we describe a plasma poor pathogen-free platelet lysate obtained by pooling 12 platelet (PLT) units, to produce a standardized and safe supplement for clinical-grade expansion of MSC. METHODS: PL lots were obtained by combining 2 6-unit PLT pools in additive solution (AS) following a transfusional-based procedure including pathogen inactivation (PI) by Intercept technology and 3 cycles of freezing/thawing, followed by membrane removal. Three PI-PL and 3 control PL lots were produced to compare their ability to sustain bone marrow derived MSC selection and expansion. Moreover, two further PL, subjected to PI or not, were also produced starting from the same initial PLT pools to evaluate the impact of PI on growth factor concentration and capacity to sustain cell growth. Additional PI-PL lots were used for comparison with fetal bovine serum (FBS) on MSC expansion. Immunoregulatory properties of PI-PL-generated MSC were documented in vitro by mixed lymphocyte culture (MLC) and peripheral blood mononuclear cells (PBMC) mitogen induced proliferation. RESULTS: PI-PL and PL control lots had similar concentrations of 4 well-described growth factors endowed with MSC stimulating ability. Initial growth and MSC expansion by PI-PL and PL controls were comparable either using different MSC populations or in head to head experiments. Moreover, PI-PL and PL control sustained similar MSC growth of frozen/thawed MSC. Multilineage differentiation of PI-derived and PI-PL-derived MSC were maintained in any MSC cultures as well as their immunoregulatory properties. Finally, no direct impact of PI on growth factor concentration and MSC growth support was observed, whereas the capacity of FBS to sustain MSC expansion in basic medium was irrelevant as compared to PL and PI-PL. CONCLUSION: The replacement of animal additives with human supplements is a basic issue in MSC ex vivo production. PI-PL represents a standardized, plasma-poor, human preparation which appears as a safe and good candidate to stimulate MSC growth in clinical-scale cultures.

Adoptive immunotherapy with cytokine-induced killer cells generated with a new good manufacturing practice-grade protocol.

BACKGROUND AIMS: We have recently shown that thymoglobulin (TG) efficiently expands cytokine-induced killer (CIK) cells in combination with interferon (IFN)-γ and interleukin (IL)-2 (ITG2 protocol). It is presently unknown whether the infusion of autologous immune effector cells generated by TG, IFN-γ and IL-2 is feasible and safe. METHODS: Five patients with advanced and/or refractory solid tumors were enrolled in the present phase I/II study. Peripheral blood mononuclear cells (PBMC) collected by leukapheresis were stimulated under good manufacturing practice (GMP)-conditions with IFN-γ, followed by TG and IL-2. After 2-3 weeks in culture, a median of 4.65 × 10(6) immune effector cells per kilogram of recipient's body weight was obtained and infused intravenously. The median time from enrollment into the study to infusion of the expanded CIK cells was 30 days. RESULTS: ITG2 efficiently expanded immune effector cells that comprised both conventional natural killer (NK) cells and CD3(+) CD16(+) CD56(+) CIK cells. One patient with advanced melanoma died because of disease progression before the infusion of CIK cells. The target dose of at least 2.5 × 10(6) CIK cells/kg of recipient's body weight was reached in four out of five evaluable patients. CIK cells were administered intravenously without any measurable toxicity. In vitro, CIK cells exerted lytic activity against cervical cancer cells. The median survival was 4.5 months (range 1-13) from the first infusion of CIK cells. CONCLUSIONS: This study has highlighted the feasibility and safety of the administration of CIK cells generated with the ITG2 protocol. Whether CIK cells can help control disease burden in patients with advanced malignancies will be determined in future clinical trials.

Polyomavirus persistence in lymphocytes: prevalence in lymphocytes from blood donors and healthy personnel of a blood transfusion centre.

BK and JC polyomaviruses (BKV and JCV) are widespread in humans and are thought to persist and reactivate under immune alterations. In addition to the kidney, lymphoid cells have been proposed as a site of latency. However, while this was shown to occur in immunocompromised patients, discordant data were published for healthy humans. To help to solve this issue, an extensive study (231 healthy subjects) was carried out on peripheral blood mononuclear cells (PBMC) from blood donors of two towns and from operators of a blood transfusion centre. To discriminate between past and recent infection, nested PCRs for BKV and JCV non-coding control region (NCCR) and VP1 DNA sequences were carried out. Twenty-two per cent of subjects had BKV NCCR, but only 7% also had BKV VP1, as detected by PCR assays of similar sensitivities; the latter positivity was found to decrease with age. In both towns, the BKV WW archetypal DDP strain, subtype I, was found. Only 0.9% of subjects contained JCV DNA, for both NCCR and VP1. Blood operators presented a statistically significant increased prevalence of BKV NCCR (3. 0-fold) and BKV VP1 (9.4-fold) sequences with respect to blood donors of comparable ages, suggesting the possibility of occupational risk of BKV (re)infection or reactivation. Since the possibility of amplifying BKV VP1 sequences from PBMC of healthy humans is lost with age, this suggests that PBMC are not a site of polyomavirus persistence in healthy individuals and that detection of BKV VP1 DNA in PBMC is probably indicative of recent infection or reactivation.