Long-term bone marrow cultures established from bone marrow transplant recipients

Following bone marrow transplantation (BMT), the stroma remains host-derived, and has therefore been exposed to the high doses of chemoradiotherapy used in BMT conditioning. We have used long term bone marrow culture (LTBMC) to study the effect of this conditioning therapy on the stroma. Twenty-five BMT recipients were studied, comprising 13 allografts and 12 autografts. Marrow was aspirated prior to transplant (6 cases) and at 3, 6 or 12 months post-BMT. Fifteen haematologically normal subjects were studied in parallel. The stromal layer of LTBMC was visually assessed at weekly intervals and supernatant cells counted and assayed for colony forming unit-granulocyte/macrophage (CFU-GM). Five of the six cases studied both before and after BMT formed less confluent stroma following the procedure. A successive improvement in the proportion of patients forming good stroma was observed with increasing time from BMT. Supernatant cell and CFU-GM counts were not significantly different from normal following BMT. No clear relationship was observed between stromal confluence and any of the following: supernatant cell and CFU-GM counts, transplant type, underlying disease, conditioning regime or time to engraftment. These data support the view that BMT conditioning regimes cause stromal damage, and that this damage gradually improves with time.