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RAPID TECHNIQUES FOR GRAFT ASSESSMENT FOLLOWING BONE MARROW TRANSPLANTATION DESIGNED FOR LARGE SCALE USE FOLLOWING ACCI- DENTAL LETHAL EXPOSURE TO RADIATION

Objective


Rapid techniques for graft assessment following bone marrow transplantation have been developed, using high information content deoxyribonucleic acid (DNA) markers and the polymerase chain reaction. These new techniques have great potential not only in assessing conditioning therapies (total body irradiation) and the role of mixed chimerism in long-term survival, but also as a means of rapid engraftment monitoring in an environmental crisis situation.
BONE MARROW TRANSPLANTATION (BMT) IS NOW THE TREATMENT OF CHOICE FOR MANY HAEMATOLOGICAL DISORDERS AND IT IS ALSO THE ONLY METHOD OF TREATMENT AVAILABLE FOR THOSE ACCIDENTALLY EXPOSED TO OTHERWISE LETHAL DOSES OF IONISING RADIATIONS. THIS SITUATION HAS ALREADY OCCURED FOLLOWING THE RECENT RUSSIAN REACTOR ACCIDENT. CURRENT METHODS FOR MONITORING ENGRAFTMENT ARE LABOUR-INTENSIVE, EXPENSIVE AND TIME-CONSUMING, REQUIRING EITHER KARYOTYPIC ANALYSIS OR ANALYSIS OF THE GENETIC MATERIAL USING CONVENTIONAL POLYMORPHIC DNA PROBES AND WOULD SERIOUSLY OVER TITRATE EXISTING ANALYTICAL FACILITIES IF REQUIRED FOR USE ON A LARGE SCALE. BOTH PROCEDURES HAVE THE ADDITIONAL DISADVANTAGE THAT THEY WILL PERMIT THE DISCRIMINATION OF HOST AND DONOR CELLS ONLY AT THE LEVEL OF 10 %.

THE AVAILABILITY OF A RAPID, SIMPLE AND RELIABLE PROCESS WHICH COULD BE EASILY USED FOR THE SIMULTANEOUS ASSESSMENT OF MULTIPLE GRAFTS IS THEREFORE HIGHLY DESIRABLE. WE HAVE DEVELOPED ONE SUCH PROCEDURE, BASED UPON THE USE OF Y-CHROMOSOME-SPECIFIC REPETITIVE ELEMENTS FOR USE IN SEX-MISMATCHED TRANSPLANTATIONS AND PROPOSE THE FURTHER DEVELOPMENT OF A SIMPLE METHOD, APPLICABLE TO ALL TRANSPLANT SITUATIONS, WHICH WILL VASTLY INCREASE THE SPEED AND EFFICIENCY WITH WHICH ENGRAFTMENT FOLLOWING BONE MARROW TRANSPLANTATION CAN BE MONITORED BY AMPLIFYING IN-VITRO POLYMORPHIC LOCI WHICH WILL PERMIT THE DISCRIMINATION OF HOST AND DONOR CELLS AT EFFICIENCIES THOUSANDS OF TIMES GREATER THAN THOSE ACHIEVABLE BY CURRENT ANALYTICAL PROCEDURES.

WHILE IN PRINCIPLE ANY POLYMORPHIC LOCI WOULD SUFFICE, THOSE CONTAINING SHORT, VARIABLE NUMBER TANDEM REPEAT SEQUENCES WILL BE OF MOST USE IN VIEW OF THEIR HIGH DEGREE OF POLYMORPHISM. LOCI WITH VARIABLE SEQUENCES CONTAINED WITHIN RESTRICTION FRAGMENTS OF LESS THAN TWO KILOBASES WILL BE SELECTED INITIALLY. WHERE NECESSARY, GENOMIC DNA SEGMENTS WILL BE SEQUENCED AND SHORT OLIGONUCLEOTIDE PRIMERS FLANKING THE VARIABLE REGIONS WILL BE SYNTHESISED. THESE WILL BE USED FOR THE IN-VITRO AMPLIFICATION OF POLYMORPHIC LOCI IN DONORS AND RECIPIENTS OF BONE MARROW TRANSPLANTS USING THERMOSTABLE DNA POLYMERASE. AMPLIFIED DNA WILL BE ANALYSED BY CONVENTIONAL SOUTHERN BLOTTING (OR BY DIRECT ANALYSIS IN ACRYLAMIDE GELS). SINCE IN-VITRO AMPLIFICATIONS IN EXCESS OF 100,000 FOLD ARE NOW ACHIEVABLE, THE ASSAY, AT ITS LIMITS, SHOULD DETECT FEWER THAN ONE HOST CELL IN 10 TO THE POWER 6 DONOR CELLS (AND VICE VERSA). IN PRACTICE, THIS MEANS THAT ANALYSES WILL BE PERFORMABLE ON VERY SMALL QUANTITIES OF MATERIAL AND WITH GREAT SPEED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

TRINITY COLLEGE
Address
College Green
Dublin 2
Ireland