15 Health Risks to Cytapheresis Donors

Optimization of platelet isolation and extraction of autogenous TGF-beta in cartilage tissue engineering

Platelets are enriched with Transforming Growth Factor-beta (TGF-beta). However, information is limited concerning TGF-beta's effects at the molecular level. Nevertheless, it has been demonstrated that TGF-beta activates cell proliferation and its positive influence on cartilage formation has been proven within the field of Tissue Engineering (TE). As Platelet Rich Plasma (PRP) contains TGF-beta, it was the purpose of this study to optimize PRP-isolation for further TGF-beta extraction. Red blood cell count (RBC) was separated from whole blood by centrifugation. From the supernatant PRP and platelet poor plasma (PPP) layer, the latter supernatant was re-centrifuged to extract PRP. Various experimental series were run to investigate influences concerning anticoagulating alternatives, different amounts of buffer, various centrifugal forces, or substituting centrifugation for sedimentation. TGF-beta levels were determined using ELISA. The technique of platelet-/ TGF-beta-extraction described here proves to be more effective than other methods, is easily repeatable and not time-consuming, which predisposes it for TE requirements.

Effect of thrombocytapheresis on blood rheology in healthy donors: role of nitric oxide

Platelet transfusions are increasingly being used to treat thrombocytopenic conditions. Because of anticoagulation, changes in blood composition and extracorporeal circulation, donor apheresis may cause alterations in hemorheology. This study aimed at investigating the effects of thrombocytapheresis on donor blood rheology. The effect of nitric oxide (NO) on donor red blood cell (RBC) deformability after thrombocytapheresis was also studied. Platelets were collected by a Haemonetics MCS 3p cell seperator. Blood samples were obtained before and 15 min after thrombocytapheresis. RBC deformability and aggregation were measured using an ektacytometer, whole blood viscosity (WBV) was determined with a cone-plate rotational viscometer. Donor RBCs were shown to be less deformable at all stress levels except 0.30 Pa after thrombocytapheresis and NO donor sodium nitroprusside (SNP, 10(-6) M) reversed the reduced deformability caused by thrombocytapheresis. It was observed that donor apheresis induces a decrement in RBC aggregation and WBV measured at standard hematocrit (Hct). No significant alterations were observed in WBV values determined at native Hct values. Thrombocytapheresis also resulted in a decrement in fibrinogen, total protein, cholesterol and albumin levels whereas Hct was found to be increased and serum glucose, triglyceride, hemoglobin levels unaltered after apheresis. These results suggest that, thrombocytapheresis causes alterations in hemorheological parameters and hence in the perfusion of the microvasculature of the donors and NO appears to have a protective effect on the impairment observed in RBC deformability.

Comparison of platelet, leukocyte, and growth factor levels in point-of-care platelet-enriched plasma, prepared using a modified Curasan kit, with preparations received from a local blood bank

The potential use of autologous thrombocytic growth factors to accelerate bone regeneration requires improved methods of isolating platelet-rich plasma (PRP). In addition to discontinuous cell separation, a second method by which PRP is produced at the point-of-care has now become available. In this study, growth factor levels in PRP from these two sources were compared. Whole blood was drawn from 115 healthy donors (73 males, 42 females) aged 21 - 62 years (mean 36, SD 10). The PRP was separated by the blood bank (BB) using the discontinuous cell separation method or at the 'point-of-care' by the so-called 'buffy coat' method (analogous to the Curasan PRP Kit). Growth factor content differed significantly for TGF-beta1 (BB 268.65+/-70.77 ng/ml, Curasan 95.02+/-60.67 ng/ml (sign test P<0.001)) and PDGF-AB (BB 133.59+/-46.26 ng/ml, Curasan 233.70+/-111.86 ng/ml (P<0.001)), while the content of IGF-I (BB 85.37+/-25.58 ng/ml, Curasan 101.72+/-47.7 ng/ml (P<0.160)) showed no significant difference. The higher thrombocyte count in the BB PRP (BB 1434300+/-351960/ microl, Curasan 908.500+/-492.30/microl) seems to result in higher TGF-beta1 levels, while the higher leukocyte count in the Curasan PRP (BB 160+/-320/ microl, Curasan 30130+/-12500/microl) seems to result in higher PDGF-AB levels. The similar IGF-I levels in the two preparations might merely reflect similar amounts of plasma in the PRP produced by each approach.

The Harvest Smart PRePTM system versus the Friadent-Schütze platelet-rich plasma kit

An important reason to improve methods for isolating platelet-rich plasma (PRP) is the potential use of autogenous platelet growth factors. In addition to the Curasan PRP kit (Curasan, Kleinostheim, Germany) and the platelet concentrated collection system (PCCSTM) system, two new methods for the preparation of PRP by the surgeon are now available. This study compared the suitability of these new methods for the preparation of PRP. Whole blood was drawn from 54 healthy donors (33 men and 21 women) aged 23-79 years (38.0 +/- 17.7 years). PRP was prepared from each donor's blood using both the Smart PRePTM system (Harvest Technologies Corporation, Munich, Germany) and the Friadent-Schütze method (PRP kit; Friadent-Schütze, Vienna, Austria). The platelet count in donor whole blood was 276 810 +/- 59 440 /microl. Platelet counts differed significantly between the Smart PRP preparation (1227 890 +/- 312 440 platelets/microl) and the Friadent-Schütze PRP preparation (1440 500 +/- 501 700 platelets/microl) (sign test, P < 0.001). The Smart PRePTM system had a significantly higher collection efficiency (63.4 +/- 7.9%) than the Friadent-Schütze kit (49.6 +/- 13.6%) (sign test, P < 0.001). The leukocyte contents in the two platelet concentrates were similar (Smart PRePTM, 19 261 +/- 8082 platelets/microl; Friadent-Schütze, 21 691 +/- 16 430). Transforming growth factor (TGF)-beta1 and platelet-derived growth factor (PDGF)-AB were higher in the Friadent-Schütze PRP (TGF-beta1, 196.8 +/- 109.6 ng/ml; PDGF-AB, 251.6 +/- 115.4 ng/ml) than in the Smart PRePTM (TGF-beta1, 77.2 +/- 54.8 ng/ml; PDGF-AB, 208 +/- 85.2 ng/ml). The sign test indicated significant differences between the two methods in the concentrations of TGF-beta1 (P < 0.001) and PDGF-AB (P < 0.01). Insulin-like growth factor (IGF)-1 levels in the two PRP preparations were similar (Friadent-Schütze PRP, 72.8 +/- 22.3 ng/ml; Smart PRePTM, 91.4 +/- 21.3 ng/ml). The Smart PRePTM system was superior with respect to ease of handling and preparation time. It also had a significantly higher platelet collection efficiency than the Friadent-Schütze PRePTM kit. The Friadent-Schütze PRP kit offers a slight advantage in the resulting PRP platelet concentration. However, this is easily compensated for in the Smart PRePTM system by reducing the volume of the resulting PRP.

Curasan PRP kit vs. PCCS PRP system. Collection efficiency and platelet counts of two different methods for the preparation of platelet-rich plasma

An important reason to improve methods of isolating platelet-rich plasma (PRP) is the potential use of autologous thrombocyte growth factors. In addition to discontinuous cell separation, two methods for extracting PRP that can be performed directly by the surgeon are now available. This study compared the suitability of these two methods for the preparation of PRP. Whole blood was drawn from 47 healthy donors (18 men, 29 women) aged 20-59 years (mean 29.9, SD 7.7). For each donor, PRP was separated by the PCCS method (PCCS Kit, 3i Implant Innovations, Palm Beach Gardens, FL, USA) and by the Curasan method (analogous to the PRP kit, Curasan, Kleinostheim, Germany). Thrombocyte counts differed significantly (sign test P = 0.001) between the donor blood (mean 290,000/ micro l, SD 86,000/ microl), the PCCS PRP preparation (mean 2,209,000/ microl, SD 901,000/ microl), and the Curasan PRP (mean 1,075,000/ micro l, SD 636,000/ microl). The correlation between the thrombocyte count in the PRP and the thrombocyte count in the donor whole blood was greater for the PCCS PRP (Spearman's correlation coefficient rS = 0.60) than for the Curasan PRP (r(S) = 0.34). A slight, clinically irrelevant, influence of gender on thrombocyte concentration in whole blood was found, but no influence of age was detected.

The collection of platelets by apheresis procedures

Collection of platelets by apheresis has been a major advance in transfusion medicine. It has allowed the supply of a therapeutically beneficial component to grow with medical needs. Donors find fulfillment in more frequent donations than are possible with whole blood and know that their donation fills a special need. New technology allows leukocyte reduction in the collection of the component with or without the use of filtration. Matching for refractory patients is possible. However, platelets collected by apheresis have not been shown to be hemostatically different from platelets separated from whole blood donations, and thus, do not represent an advance in therapeutic efficacy. The use of apheresis platelets does reduce donor exposure, but this has not been shown to be a safety advance, although it seems intuitively obvious that transfusion risk is statistically reduced in some patients requiring only a few platelet transfusions. Support of patients by apheresis platelets may or may not reduce the risk of alloimmunization. Apheresis platelets from some equipment have less white blood cell contamination even in the absence of filtration, which may be an advantage. Apheresis platelets could be a major step in the ultimate customization of blood collection, in which some donors would preferentially donate red blood cells, whereas others would donate platelets or plasma depending on their blood type and ability to donate frequently, and the current medical need of their donation. Perhaps this would be the most significant advance from the medical progress initiated by Cohn almost 50 years ago.