RR-25: Bone Loss Experiment on ISS

Astronauts exhibit significant signs of “premature osteoporosis” during spaceflight, losing up to 2% of bone density in hips and spine each month, which poses a major health challenge with long-duration spaceflight. Led by Dr. Giuseppi Initini and his team in the Pitt School of Dental Medicine, he RR-25 (Rodent Research 25) experiments on the International Space Station (ISS) aims to help address this challenge with three objectives:

  1. Develop novel therapeutic strategies to prevent, intercept , or treat spaceflight induced premature osteoporosis.
  2. Develop novel biomaterials for non-invasive or minimally invasive bone regeneration procedures to facilitate healing of bone fractures that may occur during long-duration spaceflights.
  3. More broadly, development of novel approaches for treatment of osteoporosis and for orthopaedic/dental bone regenerative procedures that may benefit humanity on Earth.

Two hypotheses are being evaluated in the RR-25 experiment, including:

  1. Microgravity impairs bone homeostasis and regeneration by inhibiting differentiation of the skeletal stem cells (SSC).
  2. Tetranite® (a novel “bone superglue” biomaterial developed by RevBio, Inc. USA), can reverse this inhibition and promote bone regeneration by stimulating SSC.

With 40 mice aboard for the ISS and 40 control mice on Earth, the RR-25 experiment launched with SpaceX-26 on November 26, 2022, operated for 45 days on the ISS, and then returned to Earth with the Dragon capsule. Since the return, studies have been underway with subjects and data from the experiment, and a set of scholarly papers is in progress for publication. 

RR-25 Slide Overview