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Reproduction of human fibrous dysplasia of bone in immunocompromised mice by transplanted mosaics of normal and Gsalpha-mutated skeletal progenitor cells.

ABSTRACT: We have isolated progenitor cells from the stromal system of the fibrous dysplastic marrow of patients with McCune-Albright Syndrome. Analysis of the Gsalpha gene from individual colonies provided direct evidence for the presence of two different genotypes within single fibrous dysplastic lesions: marrow stromal cells containing two normal Gsalpha alleles, and those containing one normal allele and an allele with an activating mutation. Transplantation of clonal populations of normal cells into the subcutis of immunocompromised mice resulted in normal ossicle formation. In contrast, transplantation of clonal populations of mutant cells always led to the loss of transplanted cells from the transplantation site and no ossicle formation. However, transplantation of a mixture of normal and mutant cells reproduced an abnormal ectopic ossicle recapitulating human fibrous dysplasia and providing an in vivo cellular model of this disease. These results provide experimental evidence for the necessity of both normal and mutant cells in the development of McCune-Albright Syndrome fibrous dysplastic lesions in bone.

SUBMITTER: Bianco P

PROVIDER: S-EPMC508756 | biostudies-other | 1998 Apr

REPOSITORIES: biostudies-other

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Reproduction of human fibrous dysplasia of bone in immunocompromised mice by transplanted mosaics of normal and Gsalpha-mutated skeletal progenitor cells.

Bianco P P Kuznetsov S A SA Riminucci M M Fisher L W LW Spiegel A M AM Robey P G PG

The Journal of clinical investigation 19980401 8

We have isolated progenitor cells from the stromal system of the fibrous dysplastic marrow of patients with McCune-Albright Syndrome. Analysis of the Gsalpha gene from individual colonies provided direct evidence for the presence of two different genotypes within single fibrous dysplastic lesions: marrow stromal cells containing two normal Gsalpha alleles, and those containing one normal allele and an allele with an activating mutation. Transplantation of clonal populations of normal cells into ...[more]

PMID: 9541505

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Project description:Fibrous dysplasia (FD) is a skeletal disease caused by somatic activating mutations of the cyclic adenosine monophosphate (cAMP)-regulating protein, α-subunit of the Gs stimulatory protein (G(s) α). These mutations lead to replacement of normal bone by proliferative osteogenic precursors, resulting in deformity, fracture, and pain. Medical treatment has been ineffective in altering the disease course. Receptor activator of NF-κB ligand (RANKL) is a cell-surface protein involved in many cellular processes, including osteoclastogenesis, and is reported to be overexpressed in FD-like bone cells. Denosumab is a humanized monoclonal antibody to RANKL approved for treatment of osteoporosis and prevention of skeletal-related events from bone metastases. We present the case of a 9-year-old boy with severe FD who was treated with denosumab for a rapidly expanding femoral lesion. Immunohistochemical staining on a pretreatment bone biopsy specimen revealed marked RANKL expression. He was started on monthly denosumab, with an initial starting dose of 1 mg/kg and planned 0.25 mg/kg dose escalations every 3 months. Over 7 months of treatment he showed marked reduction in pain, bone turnover markers (BTMs), and tumor growth rate. Denosumab did not appear to impair healing of a femoral fracture that occurred while on treatment. With initiation of treatment he developed hypophosphatemia and secondary hyperparathyroidism, necessitating supplementation with phosphorus, calcium, and calcitriol. BTMs showed rapid and sustained suppression. With discontinuation there was rapid and dramatic rebound of BTMs with cross-linked C-telopeptide (reflecting osteoclast activity) exceeding pretreatment levels, accompanied by severe hypercalcemia. In this child, denosumab lead to dramatic reduction of FD expansion and FD-related bone pain. Denosumab was associated with clinically significant disturbances of mineral metabolism both while on treatment and after discontinuation. Denosumab treatment of FD warrants further study to confirm efficacy and determine potential morbidity, as well as to determine the mechanism of RANKL in the pathogenesis of FD and related bone marrow stromal cell diseases.

Project description:Fibrous dysplasia (FD) is a mosaic disease in which bone is replaced with fibro-osseous tissue. Lesions expand during childhood, reaching final burden by age 15 years. In vitro data suggest that disease activity decreases in adulthood; however, there is no clinical data to support this concept. Bone turnover markers (BTMs) have been used as markers of disease activity in FD; however, the natural history of BTM changes, the effects of antiresorptive treatment, and their association to clinical outcomes have not been described. The goals of this study are to describe 1) the natural history of FD disease activity and its association with pain; 2) the impact of bisphosphonates on the natural history of BTMs; and 3) the effect of bisphosphonates on progression of FD burden during childhood. Disease burden scores and alkaline phosphatase, osteocalcin, NTx, FGF23, and RANKL levels from 178 subjects in an FD/MAS natural history study were reviewed, including 73 subjects treated with bisphosphonates. BTMs, RANKL, and FGF23 demonstrated a sustained reduction with age. Bisphosphonate treatment did not significantly impact this age-dependent decrease in BTMs. Pain was more prevalent and severe in adults compared with children and was not associated with BTMs. In children, the progression of disease burden was not affected by bisphosphonates. In conclusion, FD is associated with an age-dependent decline in bone turnover and other markers of disease activity. Pain, in contrast, is more frequent and severe in adults with FD and is not related to bone turnover. Bisphosphonate treatment does not significantly impact the age-dependent decrease in bone turnover, nor does it prevent the progression of FD disease burden in children. These findings, in association with the established adverse effects of antiresorptives, should be considered when evaluating use and response to bisphosphonates in patients being treated for FD and in any study using BTMs as surrogate endpoints. © 2019 American Society for Bone and Mineral Research.

Dataset Information

Reproduction of human fibrous dysplasia of bone in immunocompromised mice by transplanted mosaics of normal and Gsalpha-mutated skeletal progenitor cells.

Publications

Reproduction of human fibrous dysplasia of bone in immunocompromised mice by transplanted mosaics of normal and Gsalpha-mutated skeletal progenitor cells.

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