Hämorheologische, metabolische, physiologische und lagerungsbedingte Folgen erythrozytärer Alterung in der Normalbevölkerung und bei Typ2-Diabetes

Aim: This dissertation aimed to reproducibly examine red blood cell (RBC) ageing at different in vitro- and in vivo-conditions (health, disease, intervention by sport, cryopreservation) by fractionation into subpopulations and to detect changes in haematological, haemorheological and metabolical parameters with focus on the nitric oxide (NO)-metabolism. Additionally, these parameters should be examined on possible in vitro-differences after cryopreservation to deduce possible implications for the detection of autologous blood doping and/or in transfusion medicine.
Background: A young RBC-population in the human blood shows superior haematological, metabolical and haemorheological properties. The impact of physiological and pathophysiological changes in RBC ageing on the physiological and cellular performance has not been examined so far. Furthermore, standardised protocols for a reproducible fractionation according to age and the experimental examination are still missing. If RBC storage at cryo-temperatures (-80°C) induce age dependent side effects on the haemorheological level and if these possible side effects are relevant in vivo, could not be shown experimentally so far.
Methods: Within the context of this dissertation, four different studies were performed. Study 1: After establishing of a separation protocol, RBC from healthy controls (HC) and from type2-diabetics (DM) were separated according to age with percoll density centrifugation and examined experimentally. Differences in RBC ageing degree, deformability, NO-metabolism and ageing parameters were examined, compared and changes between HC and DM concluded. Study 2/3: Endurance untrained (AP) individuals and DM performed a moderate endurance training lasting for several weeks (AP: 6-week long running training; DM 12-week long training on a bicycle ergometer). Before and after the intervention performance related examinations were performed and the parameters of study 1 were examined in the subpopulations. With that, possible training induced changes in ageing and the properties of RBC with focus on health and disease should be detected experimentally and examined with regard to possible, practically oriented applications for preventive and rehabilitative adaptations. Study 4: Blood samples from healthy male individuals were collected and the RBC separated, prepared and cryopreserved at -80°C. Within the space of 12 weeks, blood samples from the same individuals were taken again after 4, 8 and 12 weeks and mixed after separation with stored/cryopreserved RBC in a defined ratio. The mixtures were examined on ageing markers, haemorheological, haematological and metabolic parameters and compared with fresh and stored blood samples. With this, autologous blood doping / transfusion should be mimicked in vitro to find a detection parameter by possible changes. Additional application of shear stress in a flow chamber and subsequently examination of the deformability served to simulate an in vivo-circulation system.
Results: Three distinct partial results were determined. Study 1: Type2-diabetics exhibit, besides a progressive ageing of the RBC-subpopulations, additional distinguishable metabolical and haemorheological changes with decreased deformability and changed NO-bioavailability in comparison to HC. Studie 2/3: A moderate endurance training lasting several weeks leads to rejuvenation processes in the RBC-population, improved haemorheolgical properties and performance parameters in endurance untrained men and women as well as in individuals with cardiovascular/metabolic disturbances like type2-diabetics. Study 4: Cryopreserved storage of RBC shows neither detectable changes in ageing parameters nor in the NO-metabolism, but has a great impact on haemorheological parameters, which is still detectable after an in vitro-simulation of an in vivo-transfusion.
Conclusion: The connections displayed in this dissertation show for the first time the possible “trainability” of RBC with regard to rejuvenation processes of the RBC-population and improved haemorheology. Because of the fast adaptation, moderate endurance training might be implemented on the one hand as preventive measure in healthy individuals, but on the other hand for a possible improvement of the blood flow properties in cardiovascular diseases. Haemorheological measurements might contribute to develop a detection method for autologous blood doping and to induce measures for the reduction of age-induced side effects in RBC storage. Furthermore, it can be summarized that, with regard to RBC-ageing, a complex physiological interaction is apparent which complicates the transfer of in vitro-results to real in vivo-conditions.