Osteogenesis imperfecta (OI), or ‘brittle bones disorder, is a connective tissue disorder that affects collagen, a protein that makes up much of the body’s structure. There are over 10 different types of OI, and while the severity changes from type to type, they all cause some form of increased skeletal fragility, deformity and muscle weakness.
According to researchers from the University of Missouri School of Medicine, reducing the activity of myostatin, a protein that normally stops muscles from growing too big, improved bone density in a preclinical mouse model of pregnant women with OI.
“Pregnancy and breastfeeding are already natural periods of bone density loss for women, as a baby’s growth has a large calcium demand both inside and outside the womb,” study co-author Laura Schulz said. “This can make women with OI much more prone to fractures or bone deformities, especially if they breastfeed.”
Additionally, traditional medications used to treat OI are not recommended for use during pregnancy, making alternate treatment necessary. The team found that lowering myostatin activity helped improve muscle mass and restructured bone tissue – this helps the bones withstand stress and strain without fracturing or changing shape.
“Comparing the material of OI bones to healthy bones is like Styrofoam and wood, respectively,” senior author Charlotte Phillips said. “A wooden tube will always be the hardest to break, but as a Styrofoam tube gets thicker in diameter and gains more material, it will get harder to break. We can’t change the bone’s material, since it’s decided by the person’s genetics, but we can change the structure and amount of the bone.”
Importantly, lowering myostatin did not cause any harm to the mother’s health or the child’s, which makes this a promising therapeutic opportunity for not just women with OI, but other pregnant women that may find it difficult to regain bone density.
“Understanding this intersection of women’s health, fetal development and orthopaedics is critical for the long-term musculoskeletal health of both women and children,” Schulz said. “Pregnancy is a special time, but having prior health conditions can make it complicated. Our team is investigating how to make sure that if a woman with OI wants to have a baby, she can do so in a way that is possible and safe.”
Laura Schulz, PhD is a professor of Obstetrics, Gynecology and Women's Health, Director of the OneHealth Biorepository, Director of OBGYN Research Success Core and a NextGen Precision Health Investigator. Charlotte Phillips, PhD is an emerita professor of Biochemistry, and her research focuses on the development and treatment of connective tissue disorders.
“Myostatin inhibition from preconception through lactation improves maternal muscle and skeletal health in the osteogenesis imperfecta murine mouse model” was recently published in the journal Bone. In addition to Schulz and Phillips, Mizzou study authors include Tara Crawford and Brittany Lafaver, graduate students; Bianca Davis and Isabel Chapman, undergraduate students; and Adrienne Ohler, PhD, associate professor of Applied Social Sciences. Jason Mastaitis and
