Neonatal hematopoietic stem cell transplantation cures oc/oc mice from osteopetrosis.
OBJECTIVE
Infantile malignant osteopetrosis (IMO) is a rare autosomal recessive disorder affecting osteoclast function. Fifty percent of the patients have a mutation in the TCIRG1 gene coding for one subunit of an osteoclast proton pump. The only curative treatment is hematopoietic stem cell transplantation (SCT). The oc/oc mouse has a mutation in the gene homologous to TCIRG1 and its expected lifespan is only 3 to 4 weeks. Previous attempts to cure these mice with SCT have been unsuccessful. We wanted to determine if early hematopoietic SCT using enriched and MHC-matched stem cells can cure oc/oc mice from osteopetrosis.


METHODS
One- and 8-day-old oc/oc and control mice were radiated with 200, 400, or 600 cGy and transplanted intraperitoneally with 1 or 5 x 10(6) normal lineage-depleted bone marrow cells. Blood, x-ray, and pathology analyses were performed on transplanted mice.


RESULTS
All 1-day-old mice irradiated with 400 cGy and transplanted with 5 x 10(6) cells survived long term. An engraftment level of 20% is sufficient to correct most features of the disease. X-ray and histopathology examination of transplanted animals showed normalization of bone structure. However, although a correction of bone structure occurred, the transplanted oc/oc mice were smaller in size than their littermates. In contrast to untreated animals, oc/oc mice developed teeth after transplantation, but with abnormal structure and shape making them unusable.


CONCLUSIONS
We have shown that this murine form of IMO is curable with neonatal SCT using enriched stem cells.
Johansson
Maria
M
Molecular Medicine and Gene Therapy, Lund Strategic Research Center for Stem Cell Biology and Cell Therapy, University Hospital of Lund, Lund, Sweden.
Jansson
Lina
L
Ehinger
Mats
M
Fasth
Anders
A
Karlsson
Stefan
S
Richter
Johan
J
D000818:Animals; D000831:Animals, Newborn; D019070:Cell Lineage; D004195:Disease Models, Animal; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D007263:Infusions, Parenteral; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D010022:Osteopetrosis / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D011829:Radiation Dosage; D015996:Survival Rate; D014916:Whole-Body Irradiation