Autologous cryopreserved leukapheresis cellular material for chimeric antigen receptor-T cell manufacture.

Tisagenlecleucel, a CD19-specific autologous chimeric antigen receptor (CAR)-T cell therapy, is efficacious for the treatment of relapsed/refractory B-cell precursor acute lymphoblastic leukemia and diffuse large B-cell lymphoma. The tisagenlecleucel manufacturing process was initially developed in an academic setting and subsequently transferred to industry for qualification, validation and scaling up for global clinical trials and commercial distribution. Use of fresh leukapheresis material was recognized early on in the transfer process as a challenge with regard to establishing a global supply chain. To maximize manufacturing success rates and to overcome logistical challenges, cryopreservation was adapted into the Novartis manufacturing process from the beginning of clinical trials. Tisagenlecleucel manufactured in centralized facilities with cryopreserved leukapheresis material has been used successfully in global clinical trials at more than 50 clinical centers in 12 countries. Cryopreservation provides flexibility in scheduling leukapheresis when the patient's health is optimal to provide T cells; it also provides protection from external factors, such as shipping delays, and removes manufacturing time constraints. Several studies were performed to establish comparability of fresh versus cryopreserved leukapheresis material, to evaluate and optimize the cryopreservation process, to determine the optimal temperature and maximum hold time prior to cryopreservation and to determine the optimal temperature range for shipment and storage. Using the current validated industry manufacturing process, high success rates were achieved with regard to manufacturing tisagenlecleucel batches that met specifications and were released to patients. Consistent product quality and positive clinical outcomes support the use of cryopreserved non-mobilized peripheral mononuclear blood cells collected using leukapheresis for CAR-T cell manufacturing.

Automated Good Manufacturing Practice-compliant generation of human monocyte-derived dendritic cells from a complete apheresis product using a hollow-fiber bioreactor system overcomes a major hurdle in the manufacture of dendritic cells for cancer vaccines.

BACKGROUND: Although dendritic cell (DC)-based cancer vaccines represent a promising treatment strategy, its exploration in the clinic is hampered due to the need for Good Manufacturing Practice (GMP) facilities and associated trained staff for the generation of large numbers of DCs. The Quantum bioreactor system offered by Terumo BCT represents a hollow-fiber platform integrating GMP-compliant manufacturing steps in a closed system for automated cultivation of cellular products. In the respective established protocols, the hollow fibers are coated with fibronectin and trypsin is used to harvest the final cell product, which in the case of DCs allows processing of only one tenth of an apheresis product. MATERIALS AND RESULTS: We successfully developed a new protocol that circumvents the need for fibronectin coating and trypsin digestion, and makes the Quantum bioreactor system now suitable for generating large numbers of mature human monocyte-derived DCs (Mo-DCs) by processing a complete apheresis product at once. To achieve that, it needed a step-by-step optimization of DC-differentiation, e.g., the varying of media exchange rates and cytokine concentration until the total yield (% of input CD14+ monocytes), as well as the phenotype and functionality of mature Mo-DCs, became equivalent to those generated by our established standard production of Mo-DCs in cell culture bags. CONCLUSIONS: By using this new protocol for the Food and Drug Administration-approved Quantum system, it is now possible for the first time to process one complete apheresis to automatically generate large numbers of human Mo-DCs, making it much more feasible to exploit the potential of individualized DC-based immunotherapy.

Treating inflammatory bowel disease by adsorptive leucocytapheresis: a desire to treat without drugs.

Ulcerative colitis and Crohn's disease are the major phenotypes of the idiopathic inflammatory bowel disease (IBD), which afflicts millions of individuals throughout the world with debilitating symptoms, impairing function and quality of life. Current medications are aimed at reducing the symptoms or suppressing exacerbations. However, patients require life-long medications, and this can lead to drug dependency, loss of response together with adverse side effects. Indeed, drug side effects become additional morbidity factor in many patients on long-term medications. Nonetheless, the efficacy of anti-tumour necrosis factors (TNF)-α biologics has validated the role of inflammatory cytokines notably TNF-α in the exacerbation of IBD. However, inflammatory cytokines are released by patients' own cellular elements including myeloid lineage leucocytes, which in patients with IBD are elevated with activation behaviour and prolonged survival. Accordingly, these leucocytes appear logical targets of therapy and can be depleted by adsorptive granulocyte/monocyte apheresis (GMA) with an Adacolumn. Based on this background, recently GMA has been applied to treat patients with IBD in Japan and in the European Union countries. Efficacy rates have been impressive as well as disappointing. In fact the clinical response to GMA seems to define the patients' disease course, response to medications, duration of active disease, and severity at entry. The best responders have been first episode cases (up to 100%) followed by steroid naïve and patients with a short duration of active disease prior to GMA. Patients with deep ulcers together with extensive loss of the mucosal tissue and cases with a long duration of IBD refractory to existing medications are not likely to benefit from GMA. It is clinically interesting that patients who respond to GMA have a good long-term disease course by avoiding drugs including corticosteroids in the early stage of their IBD. Additionally, GMA is very much favoured by patients for its good safety profile. GMA in 21st century reminds us of phlebotomy as a major medical practice at the time of Hippocrates. However, in patients with IBD, there is a scope for removing from the body the sources of pro-inflammatory cytokines and achieve disease remission. The bottom line is that by introducing GMA at an early stage following the onset of IBD or before patients develop extensive mucosal damage and become refractory to medications, many patients should respond to GMA and avoid pharmacologics. This should fulfill the desire to treat without drugs.

Questionnaire based assessment of patients' acceptability of leukocytapheresis for the treatment of inflammatory bowel disease.

The aim of the present study was to assess patients' acceptance of therapeutic leukocytapheresis known as cytapheresis (CAP) for the treatment of an active flare of inflammatory bowel disease (IBD). A questionnaire was sent to 155 IBD patients who had been treated with CAP for an active flare of IBD at the IBD center of Hyogo College of Medicine between January 2009 and July 2012. In the questionnaire, patients were asked to evaluate CAP including efficacy, safety, unfavorable features and their willingness to be retreated with CAP for a subsequent IBD flare-up. Seventy-eight percent (112 of 155 patients) including 86 with ulcerative colitis and 26 with Crohn's disease completed the questionnaire. The need for coming to hospital for CAP, needle pain during blood access, sparing time for CAP process were scored by 57%, 58%, and 58.9% of the patients, respectively as unfavorable. Patients highly favored the safety of CAP, the sum of very and relatively favorable was 89%, higher than for efficacy (68%). Seventy-two percent of patients favored retreatment with CAP. In binary logistic regression analysis, the levels of satisfaction for efficacy (P < 0.001), and inconvenience for CAP treatment time (P < 0.001) were highly significant factors for patients' willingness to be retreated. Bearing in mind that CAP is a non-pharmacologic treatment intervention, our analyses indicated that IBD patients favored high efficacy, as well as comfort of CAP or maintaining their normal social activity even during an active phase of the disease. Patient's acceptability for CAP appeared to be determined by the balance of these factors.

Efficacy, safety and cost analyses in ulcerative colitis patients undergoing granulocyte and monocyte adsorption or receiving prednisolone.

BACKGROUND: Patients with ulcerative colitis (UC) are treated with prednisolone (PSL), which causes adverse side effects. Extracorporeal granulocyte/monocyte adsorption (GMA) with an Adacolumn depletes elevated/activated myeloid lineage leucocytes as sources of inflammatory cytokines. We were interested to evaluate the efficacy, safety and the treatment cost for PSL and GMA. METHODS: Forty-one patients with active UC had achieved remission with GMA, at 1 or 2 sessions/week, up to 10 sessions (n=24) or with orally administered PSL (1mg/kg bodyweight, n=17). Clinical activity index (CAI) ≤4 was considered clinical remission. Following remission, patients received 5-aminosalicylic acid (2250-3000mg/day) or sulphasalazine (4000-6000mg/day) as maintenance therapy and were followed for 600 days. The total treatment cost was assessed based on 1€=150JPY. RESULTS: PSL was tapered after two weeks, and discontinued when a patient achieved remission. The average time to the disappearance of at least one major UC symptom (haematochezia, diarrhoea, or abdominal discomfort) was 15.3 days in the GMA group and 12.7 days in the PSL group, while time to remission was 27.9 days in the GMA group and 27.6 days in the PSL group, CAI 0.8 and 2.0, respectively. The Kaplan-Meier plots showed similar remission maintenance rates over the 600 days follow-up period. The average medical cost was 12739.4€/patient in the GMA group and 8751.3€ in the PSL group (P<0.05). In the GMA group, 5 transient adverse events were observed vs 10 steroid related adverse events in the PSL group (P<0.001). CONCLUSIONS: In appropriately selected patients, GMA has significant efficacy with no safety concern. The higher cost of GMA vs PSL should be compromised by good safety profile of this non-pharmacological treatment intervention.

Stochastic cellular automata model and Monte Carlo simulations of CD4+ T cell dynamics with a proposed alternative leukapheresis treatment for HIV/AIDS.

Acquired Immunodeficiency Syndrome (AIDS) is responsible for millions of deaths worldwide. To date, many drug treatment regimens have been applied to AIDS patients but none has resulted in a successful cure. This is mainly due to the fact that free HIV particles are frequently in mutation, and infected CD4(+) T cells normally reside in the lymphoid tissue where they cannot (so far) be eradicated. We present a stochastic cellular automaton (CA) model to computationally study what could be an alternative treatment, namely Leukapheresis (LCAP), to remove HIV infected leukocytes in the lymphoid tissue. We base our investigations on Monte Carlo computer simulations. Our major objective is to investigate how the number of infected CD4(+) T cells changes in response to LCAP during the short-time (weeks) and long-time (years) scales of HIV/AIDS progression in an infected individual. To achieve our goal, we analyze the time evolution of the CD4(+) T cell population in the lymphoid tissue (i.e., the lymph node) for HIV dynamics in treatment situations with various starting times and frequencies and under a no treatment condition. Our findings suggest that the effectiveness of the treatment depends mainly on the treatment starting time and the frequency of the LCAP. Other factors (e.g., the removal proportion, the treatment duration, and the state of removed cells) that likely influence disease progression are subjects for further investigation.

Multiple myeloma patients receiving large volume leukapheresis efficiently yield enough CD34+ cells to allow double transplants.

Current protocols for myeloma patients require more than one autologous transplant. We performed a retrospective study to determine the cost-effectiveness of large volume leukapheresis (LVL) compared with standard volume leukapheresis (SVL) collection when two transplants are required. We evaluated 87 patients who underwent a cumulative total of 260 LVL and SVL collections. The median product volume per collection was 356 ml for LVL, and this was significantly higher than the median product volume per collection for SVL (median 149.5 ml, P < 0.001). The median total CD34+ cell yield/kg was 6.4 x 10(6) for LVL and 5.2 x 10(6) for SVL. This difference was statistically significant (P = 0.005). Because the target CD34+ cell dose for a single transplant was 3 x 10(6)/kg at our institution, overall the LVL yields enough CD34+ cells that could allow for two transplants. Therefore, more patients in the LVL group were able to undergo a potential second transplant. Because of the reserved cells for a second transplant, LVL patients received significantly less CD34+ cell/kg per transplant than the patients in SVL group (P = <0.001). As a result, LVL group had statistically significant but clinically insignificant delay in neutrophil (P = <0.001) and platelet (P = 0.02) engraftments. Additionally, using LVL instead of SVL to collect >or=6 x 10(6)/kg CD34+ cells may potentially save $7,497 per patient. We therefore conclude that LVL is the method of choice for collection of multiple myeloma patients when two transplants are anticipated.

EPO in combination with G-CSF improves mobilization effectiveness after chemotherapy with ifosfamide, epirubicin and etoposide and reduces costs during mobilization and transplantation of autologous hematopoietic progenitor cells.

A successful stem cell harvest is a prerequisite for peripheral blood SCT. We investigated the number of CD34(+) cells mobilized, the number of leukaphereses needed and the expenses of treatment for 28 patients with multiple myeloma randomly assigned to receive either G-CSF alone or G-CSF+EPO for stem cell mobilization after chemotherapy with ifosfamide, epirubicin and etoposide. All patients treated with G-CSF+EPO reached the threshold of 6 x 10(6) CD34(+) cells per kg body weight (kgbw), with a mean of 1.3 leukaphereses. On average 15.4 x 10(6) CD34(+) cells/kgbw were collected. In the G-CSF-alone group, the mean number of leukaphereses was 1.8, and 12.6 x 10(6) CD34(+) cells/kgbw were collected, and two patients failed the threshold. Overall costs per patient for mobilization and leukaphereses were 8339 euro (G-CSF+EPO) and 8842 euro (G-CSF). After transplantation, fewer blood transfusions (0.6 versus 1.3, P=0.05), fewer days on antibiotics (2.3 versus 6.1, P=0.02) and a shorter hospital stay (15.2 versus 17.8, P=0.06) were noted in the G-CSF+EPO group resulting in a 19.2% reduction of costs for each transplant (P=0.018). In summary, EPO improves the mobilization efficiency of G-CSF and so reduces costs of mobilization and SCT.

Evaluation of 'out-of-specification' CliniMACS CD34-selection procedures of hematopoietic progenitor cell-apheresis products.

BACKGROUND: Immunomagnetic selection of CD34(+) hematopoietic progenitor cells (HPC) using CliniMACS CD34 selection technology is widely used to provide high-purity HPC grafts. However, the number of nucleated cells and CD34+ cells recommended by the manufacturer for processing in a single procedure or with 1 vial of CD34 reagent is limited. METHODS: In this retrospective evaluation of 643 CliniMACS CD34-selection procedures, we validated the capacity of CliniMACS tubing sets and CD34 reagent. Endpoints of this study were the recovery and purity of CD34+ cells, T-cell depletion efficiency and recovery of colony-forming units-granulocyte-macrophage (CFU-GM). RESULTS: Overloading normal or large-scale tubing sets with excess numbers of total nucleated cells, without exceeding the maximum number of CD34+ cells, had no significant effect on the recovery and purity of CD34+ cells. In contrast, overloading normal or large-scale tubing sets with excess numbers of CD34+ cells resulted in a significantly lower recovery of CD34+ cells. Furthermore, the separation capacity of 1 vial of CD34 reagent could be increased safely from 600 x 10(6) CD34+ cells to 1000 x 10(6) CD34+ cells with similar recovery of CD34(+) cells. Finally, T-cell depletion efficiency and the fraction of CD34+ cells that formed CFU-GM colonies were not affected by out-of-specification procedures. DISCUSSION: Our validated increase of the capacity of CliniMACS tubing sets and CD34 reagent will reduce the number of selection procedures and thereby processing time for large HPC products. In addition, it results in a significant cost reduction for these procedures.

Treatment cost of ulcerative colitis is apheresis with Adacolumn cost-effective?

BACKGROUND: Scarce data are available in Europe on the cost of treatment for ulcerative colitis (UC). AIM: To assess the cost of illness of moderate-to-severe UC in two scenarios: traditional treatment versus alternative treatment incorporating granulocyte, monocyte adsorption - apheresis (GMA-Apheresis; Adacolumn). To determine the relative cost-effectiveness of both options in steroid-dependent patients. METHODS: One-year cost-of-illness and cost-effectiveness analysis from the third-payer perspective using a decision tree model was carried out. Probabilities of each event were derived from the literature and an expert panel. Direct medical costs were obtained from official sources (euro2004). Effectiveness was measured by the proportion of patients achieving clinical remission. RESULTS: The average annual cost per patient treated with traditional treatment was estimated to be euro6740; with GMA-Apheresis, the cost was estimated to be euro6959. In steroid-dependent patients, the average annual cost was euro6059 and euro11,436, respectively. The proportion of patients achieving clinical remission with GMA-Apheresis was 22.5% higher. As second- and third-line therapy, a new course of corticosteroids and surgery was avoided in 18.5 and 4% of patients, respectively. CONCLUSIONS: Incorporating GMA-Apheresis (Adacolumn) in the therapeutic management of moderate-to-severe UC patients is cost-effective and implies savings related to the reduction of adverse effects derived from corticosteroid use and to the decreased number of surgical interventions.

Mobilization strategies for the collection of peripheral blood progenitor cells: Results from a pilot study of delayed addition G-CSF following chemotherapy and review of the literature.

OBJECTIVE: Given the potential to limit cost, we conducted a pilot study evaluating delayed, low-dose granulocyte colony-stimulating factor (G-CSF) following chemotherapy for the procurement of peripheral blood progenitor cells (PBPCs) for autologous transplantation and reviewed the relevant literature. PATIENTS AND METHODS: Twenty-eight patients with various malignancies received cyclophosphamide 4 gm/m(2) and paclitaxel 170 mg/m2 followed by G-CSF 300 microg/d or 480 microg/d starting day +5 until two to four daily large volume leukapheresis yielded > or =5.0 x 10(6) CD34+ cells. We searched MEDLINE, Pubmed, and EMBASE databases from 1990 to the present to identify papers on PBPC procurement using delayed G-CSF (starting day +4 or later) following chemotherapy. RESULTS: G-CSF was administered for a median of 9 days at an average cost of 1260 USD per 70-kg patient. Collection was initiated at a median of 12 days after chemotherapy. A median 2.5 (range 2-4) apheresis were performed yielding an average daily CD34+ collection of 6.9 x 10(6)/kg (range 0.35-56.7). After one apheresis, 82% and 57% of patients collected > or =2.5 x 10(6)/kg and > or =5.0 x 10(6)/kg, respectively. Ultimately, 89% collected > or =5.0 x 10(6)/kg. Febrile neutropenia and catheter-related infection developed in five and two patients, respectively. All patients proceeded to transplantation and engrafted successfully with a median of 14.9 x 10(6)/kg (range 1.05-113) cells infused. Eleven published reports were identified involving 590 patients of whom 498 received G-CSF at a dose range of 250 microg/d to 10 microg/kg/d starting day +4 to 15 for a period of 4 to 9 days for PBPC procurement. Among these reports, 62 to 100% and 33 to 96% of patients collected > or =2 to 2.5 x 10(6) and > or =5.0 x 10(6) CD34+ cells, respectively. CONCLUSION: The use of delayed, low-dose G-CSF plus chemotherapy for stem cell mobilization was feasible and provides further evidence supporting this potentially cost-effective strategy. A review of the literature supports our findings and emphasizes the need for larger studies to address this issue.

Implementation of peripheral blood CD34 analyses to initiate leukapheresis: marked reduction in resource utilization.

BACKGROUND: Analysis of the peripheral blood (PB) C34 value may determine the optimal time to initiate leukapheresis. STUDY DESIGN AND METHODS: After selecting a threshold PB CD34 value of five CD34 + cells per microL to initiate leukapheresis procedure, a prospective analysis of 50 consecutive patients was initiated to identify the optimal time to initiate leukapheresis and its impact on costs and resource utilization. Clinical decisions were made to commence or to postpone leukapheresis with this PB CD34 threshold number. Based on PB CD34 values for each patient, the number of leukapheresis procedures, postponed or canceled, the number of CD34+ cells per kg, and the total number of cells collected were identified. Costs of mobilization were obtained from the hospital cost accounting system. RESULTS: In 13 months, 50 patients with a hematologic disorder underwent mobilization. There were 34 cancellations or postponements of collections due to a low PB CD34 value in 13 patients. By use of our identified costs per initial collection, this resulted in a savings of 67,660 US dollars. CONCLUSIONS: This prospective study defines how the implementation of the PB CD34 value results in costs savings. A low PB CD34 value canceled or postponed a significant number of leukapheresis procedures, resulting in a substantial cost savings. Use of the PB CD34 value should be the standard of care during mobilization and peripheral blood progenitor cell collection.

A randomized trial of assessment of efficacy of leukapheresis volumes, 8 liters vs 12 liters.

It is logical to expect that large-volume leukapheresis may be able to collect adequate numbers of PBSC with fewer procedures. To date, there is no agreement on the optimal volume of leukapheresis. Therefore, in this study we compared 8 l volume with 12 l and assessed whether a 50% increase in the blood volume processed would decrease the number of leukaphereses each patient needed to collect > or =2.5 x 10(6) CD34(+) cells/kg in normal mobilizers. PBSC mobilization was done with cyclophosphamide etoposide followed by rhG-CSF in all patients. Forty patients were randomized to undergo 8 l leukaphereses (n = 20 patients) or 12 l leukaphereses (n = 20). The median numbers of leukaphereses required in order to collect > or =2.5 x 10(6) CD34(+) cells/kg in patients processed with 8 l and 12 l were 1 (range 1-5) and 1 (1-4), respectively (P = 0.50). The median number of total nucleated cells (TNC) collected per patient was greater for the 12 l group (7.47 x 10(8)/kg vs 3.90 x 10(8)/kg, P < 0.001), as was the median number of total mononuclear cells (TMNC) (4.26 x 10(8)/kg vs 2.16 x 10(8)/kg, P < 0.001), whereas there was no difference between the two groups for the median number of CD34(+)cells collected per patient (8.94 x 10(6)/kg vs 8.60 x 10(6)/kg, P = 0.85). The TNCs and TMNCs collected per leukapheresis were again greater for the 12 l group (3.64 x 10(8)/kg vs 1.91 x 10(8)/kg, P = 0.001 and 2.17 x 10(8)/kg vs 0.88 x 10(8)/kg, P < 0.001), whereas there was no difference between the two groups for the median number of CD34(+) cells collected per leukapheresis (3.98 x 10(6)/kg vs 3.26 x 10(6)/kg, P = 0.90). This study showed that there is no difference between 8 l and 12 l volumes in regard to collected CD34(+) cells/kg and also the use of a 12 l leukapheresis volume did not decrease the number of leukaphereses performed compared with a 8 l leukapheresis volume. In fact, the use of the larger leukapheresis volume had the disadvantage of adding 60 min to the time the patient was on the machine.

Intraoperative treatment strategy to reduce the incidence of postcardiopulmonary bypass atrial fibrillation.

PURPOSE: Postcardiopulmonary bypass atrial fibrillation remains a constant complication associated with coronary revascularization, the incidence of which occurs from 20% to 35%. Previous studies have addressed this problem in the postoperative setting utilizing pharmacological agents, but the results have been variable. The purpose of this study was to evaluate a novel intraoperative strategy to reduce the incidence of postcardiopulmonary bypass atrial fibrillation. We theorized that leukocyte depletion by filtration with the addition of aprotinin would reduce the systemic inflammatory effects of bypass and reduce the incidence of atrial fibrillation. METHODS: One hundred and twenty-two patients participated in this randomized study. Only isolated primary coronary revascularization procedures on cardiopulmonary bypass were included. The control group (n=55) received standard moderate hypothermic blood cardioplegia cardiopulmonary bypass. The treatment group (n=65) received similar cardiopulmonary bypass with the addition of strategic leukocyte depletion with Pall Biomedical Products (East Hills, NY) leukodepletion filters and full-dose aprotinin. RESULTS: The intraoperative addition of leukocyte depletion by filtration with aprotinin reduced the incidence of postcardiopulmonary bypass atrial fibrillation by 72%. The incidence.of atrial fibrillation in the control group was 27% (15 of 55). In contrast, the occurrence of atrial fibrillation in the treated group was only 7.6% (5 of 65) (p<0.025). CONCLUSIONS: This novel intraoperative treatment strategy of both mechanical (leukocyte filtration) and pharmacological (aprotinin) intervention appears to markedly reduce the incidence of postcardiopulmonary bypass atrial fibrillation. To our knowledge, this is the first study to combine these two treatment strategies. A previous study has noted a decline in atrial fibrillation with aprotinin in the animal model, but not to the extent observed in our study. The beneficial effects of the reduction of atrial fibrillation include reduced risk of emboli formation and the incidence of ischemia in the heart, lung and brain. In addition, a decrease in length of hospital stay, recovery time and overall cost occurred.

Processing of peripheral blood progenitor cell components in improved clean areas does not reduce the rate of microbial contamination.

BACKGROUND: Microbial contamination of peripheral blood progenitor cell components (PBPCs) may cause severe complications in immunosuppressed recipients. Therefore, principles of Good Manufacturing Practice (GMP) are applicable for processing of PBPC components to reduce potential risks of contamination. STUDY DESIGN AND METHODS: It was investigated in a retrospective study whether the microbial contamination of PBPC components could be reduced after processing in improved clean areas according to the "Manufacture of Sterile Medicinal Products." Starting in 1994, a total of 1478 autologous and allogeneic PBPC components have been collected and processed into 3149 cryopreservation bags at the Department of Transfusion Medicine. Sterility testing was performed for all bags. Until December 1998, 783 PBPC components were processed at a clean bench only (group I). Thereafter, 695 PBPC components have been processed at a clean bench located in a clean area with an airlock system for personnel and equipment (group II). RESULTS: In group I, 16 of 1555 bags (1.03%) showed positive results in the first sterility testing. In group II, 21 of 1594 bags (1.32%) were positive (p = NS). The clinical follow-up was inconspicuous. CONCLUSION: Microbial contamination of PBPC components could not be reduced by installation of improved clean area conditions.