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Updated: Sep 1, 2025
Bone Marrow Transplantation Procedures in Mice to Study Clonal Hematopoiesis
Published on: May 26, 2021
Bone marrow transplantation as a therapy for autosomal dominant osteopetrosis type 2 in mice
Imranul Alam1, Rita L Gerard-O'Riley1, Dena Acton1
1Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Abstract:
Autosomal dominant osteopetrosis type II (ADO2) is a heritable bone disease of impaired osteoclastic bone resorption caused by missense mutations in the chloride channel 7 (CLCN7) gene. Clinical features of ADO2 include fractures, osteomyelitis of jaw, vision loss, and in severe cases, bone marrow failure. Currently, there is no effective therapy for ADO2, and patients usually receive symptomatic treatments. Theoretically, bone marrow transplantation (BMT), which is commonly used in recessive osteopetrosis, could be used to treat ADO2, although the frequency of complications related to BMT is quite high. We created an ADO2 knock-in (p.G213R mutation) mouse model on the 129 genetic background, and their phenotypes mimic the human disease of ADO2. To test whether BMT could restore osteoclast function and rescue the bone phenotypes in ADO2 mice, we transplanted bone marrow cells from 6-8 weeks old male WT donor mice into recipient female ADO2 mice. Also, to determine whether age at the time of transplant may play a role in transplant success, we performed BMT in young (12-week-old) and old (9-month-old) ADO2 mice. Our data indicate that ADO2 mice transplanted with WT marrow achieved more than 90% engraftment up to 6 months post-transplantation at both young and old ages. The in-vivo DXA data revealed that young ADO2 mice transplanted with WT marrow had significantly lower whole body and spine areal bone mineral density (aBMD) at month 6 post-transplantation compared to the ADO2 control mice. The old ADO2 mice also displayed significantly lower whole body, femur, and spine aBMD at months 4 and 5 post-transplantation compared to the age-matched control mice. The in-vivo micro-CT data showed that ADO2 experimental mice transplanted with WT marrow had significantly lower BV/TV at months 2 and 4 post-transplantation compared to the ADO2 control mice at a young age. In contrast, ADO2 control and experimental mice displayed similar BV/TV values for all post-transplantation time points at old age. In addition, serum CTX was significantly higher at month 2 post-transplantation in both young and old ADO2 experimental mice compared to the ADO2 control mice. Serum P1NP levels in young ADO2 experimental mice were significantly higher at baseline and month 2 post-transplantation compared to the ADO2 control mice. These data suggest that BMT may provide, at least, some beneficial effect at both young and adult ages.
Insights
Bone marrow transplantation (BMT) in mice with autosomal dominant osteopetrosis type II (ADO2) showed some benefits. This study explored BMT as a potential therapy for ADO2, a rare genetic bone disorder.
Area of Science:
- Genetics and Molecular Biology
- Skeletal Biology and Disease
- Hematology and Immunology
Background:
- Autosomal dominant osteopetrosis type II (ADO2) is a rare genetic disorder characterized by impaired osteoclast function due to mutations in the CLCN7 gene.
- Current treatments for ADO2 are primarily symptomatic, with no definitive cure available.
- Bone marrow transplantation (BMT), a standard treatment for recessive osteopetrosis, is theoretically applicable to ADO2 but carries a high risk of complications.
Purpose of the Study:
- To evaluate the efficacy of bone marrow transplantation (BMT) in restoring osteoclast function and ameliorating bone phenotypes in a mouse model of ADO2.
- To investigate the impact of recipient age (young vs. old) on the success and outcomes of BMT in ADO2 mice.
Main Methods:
- An ADO2 knock-in mouse model (p.G213R mutation) was utilized, exhibiting phenotypes consistent with human ADO2.
- Wild-type (WT) bone marrow cells were transplanted into young (12-week-old) and old (9-month-old) ADO2 recipient mice.
- Engraftment rates, bone mineral density (DXA), bone structure (micro-CT), and serum bone turnover markers (CTX, P1NP) were assessed post-transplantation.
Main Results:
- Successful engraftment (>90%) was achieved in both young and old ADO2 mice receiving WT marrow up to 6 months post-transplantation.
- Transplanted young ADO2 mice showed reduced bone mineral density and altered bone structure compared to controls, while old ADO2 mice showed reduced bone mineral density but similar bone structure.
- Elevated serum CTX and P1NP levels in transplanted mice suggest increased bone resorption and formation, indicating some therapeutic effect.
Conclusions:
- Bone marrow transplantation demonstrates potential therapeutic benefits in an ADO2 mouse model, even in adult animals.
- While BMT may not fully normalize bone phenotypes, it appears to influence bone turnover, suggesting it could be a viable treatment option for ADO2.
- Further research is warranted to optimize BMT protocols and assess long-term efficacy and safety for ADO2 patients.
