Strategy and tactics for stimulation of haemopoiesis in patients developing the acute radiation syndrome. Chapter 8

This paper is essentially based on the outcome of a concerted research action of the European Communities entitled 'Medical Treatment Protocols for Radiation Accident Victims as a Basis for a Computerized Guidance System' (METREPOL) which was conducted as a joint effort between research establishments in Paris, Oxford, Rotterdam, Munich and Ulm. The results of this concerted action have been published by the British Institute of Radiology in 2001 with the following title: 'Medical Management of Radiation Accidents: Manual on the Acute Radiation Syndrome'. In this manual, experience was used from more than 800 case histories of persons that were subjected to whole body radiation exposure during radiation accidents. A total of 70 accidents in 14 countries provided the material for the manual including data on medical management and follow-up of the Chernobyl and Tokaimura accidents presented in detail in this Technical Document. These case histories form the core of an international database system entitled SEARCH (System for Evaluation and Archiving of Radiation Accidents based on Case Histories). The haematopoietic cell renewal systems are of paramount importance in the clinical management of the acute radiation syndrome for two reasons. First of all, the haematopoietic tissue is distributed throughout the skeleton characterized by an enormous haematopoietic cell turnover as well as by a high radiation sensitivity. Furthermore, it is regulated to act as one organ by humoral factors and by a continuous monitoring of stem cell content in the bone marrow units by a migration stream of circulating haematopoietic stem cells. Therefore, the haematopoietic blood cell response patterns after total body exposure to ionizing radiation reflect in a very precise way the extent of damage to the entire organism and are able to predict the probable clinical course of the patient and allows preparation for the different treatment options. Thus, it is obvious that the haematopoietic cell renewal system is of high diagnostic significance in the management of the acute radiation syndrome. Secondly, the haematopoietic tissue is also of crucial importance for the principle survival chance of an exposed person. If haematopoietic regeneration can be achieved, then other organ radiation impairments may well have a chance to be successfully treated. Due to modern treatment options such as stem cell transplantation as well as growth factor therapy, the vulnerability of the haematopoietic system is not any longer the limiting factor in radiation accident survival of victims. The critical question that remains is whether the subsequent multiorgan damage can be overcome by appropriate therapeutic methods. Therefore, this paper presents first the structure and function of the haematopoietic cell renewal systems and their relevance for the acute radiation syndrome. Secondly, it addresses the question of the strategic approaches to assess the severity of radiation injury to haematopoiesis. And thirdly, it is its purpose to briefly summarize the approaches to treat haematological consequences of whole body radiation exposure