ISS Science for Everyone
Science Objectives for Everyone
Only a few animals like tadpoles and salamanders can regrow a lost limb, but the onset of this process exists in all vertebrates. Tissue Regeneration-Bone Defect (Rodent Research-4 (CASIS)) studies what prevents other vertebrates such as rodents and humans from regrowing lost bone and tissue, and how the microgravity extraterrestrial condition impacts the process. Results provide a new understanding of the biological reasons behind humans’ inability to grow a lost limb at the wound site, and could lead to tissue regeneration efforts in space.
Science Results for Everyone
The following content was provided by Rasha Hammamieh, Ph.D., and is maintained in a database by the ISS Program Science Office.
OpNom: Rodent Research-4
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Rasha Hammamieh, Ph.D., United States Army, Ft. Detrick, MD, United States
Nabarun M. Chakraborty, M.S., M.B.A., US Army, Ft. Detrick, MD, United States
Melissa Kacena, Ph.D., Indiana University School of Medicine, Indianapolis, IN, United States
Marti Jett, Ph.D., United States Army, Ft. Detrick, MD, United States
US Army Center for Environmental Health Research, Frederick, MD, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
National Laboratory (NL)
Earth Benefits, Scientific Discovery, Space Exploration
ISS Expedition Duration
- February 2017
Comprehensive knowledge about tissue regeneration may lead to defining a plausible mechanism of limb regeneration at the wound site, which is a common aptitude typically exercised by many lower ranked vertebrates like the salamander (to note, human embryos also have a similar capability which is lost in the course of maturity).
Lower gravity provides some beneficial effects on the tissue regeneration process. It is therefore warranted to understand the biological interpretation of the healing/ tissue regeneration process in spaceflight. In addition, the therapeutic success of certain agents capable of inducting healing/tissue regeneration is gauged in the spaceflight.
For Tissue Regeneration-Bone Defect (Rodent Research-4 [CASIS]) a pre-flight surgery is performed to the rodents’ femurs to create an artificial defect, which is filled with (or without) certain osteoinductive agents. The healing efficacy is monitored in terrestrial and extraterrestrial environments.
Transcriptomics, genomics, proteomics, metabolomics and microbiomics aspects of the selected biomaterials critical for healing/ tissue regeneration are evaluated. The pan-omics results are sorted and integrated; enriched circuits and ontologies are mined by a set of heuristic algorithms.
The deliverables may help to explain the overall impact of microgravity on healing/ tissue regeneration. The potential effects of microgravity on the inductive agents of wound healing are determined.
In the long term, the knowledge may lead to understanding the biological reasons behind our inability to grow a lost limb at the wound site despite the fact that the initial onset of this process is the same across all vertebrates, including salamander, and the possibility of achieving this feat in a microgravity environment.
Reduced gravity induces cell proliferation and propagation; a potent environment for tissue regeneration. In fact, salamanders housed in reduced gravity demonstrated a better quality of limb regeneration. Leveraging from these reports, the present study is set to explore the biological interpretations of the microgravitational impacts on the tissue regeneration.
The knowledge could help in evaluating the practicality of carrying out tissue regeneration programs in future spaceflights. Molecular circuits and/or markers with therapeutic significance associated with microgravity mediated wound healing/ tissue regeneration could be identified. The pan-omics interpretation may also help in comprehending the reasons of osteoporosis, a typical ailment suffered by the space travelers. It is interesting to note that vertebrates in general display a similar initial response to a wound or amputation; however at the end, only certain vertebrates like salamander and tadpole are able to generate complex tissue/ limb at the wound sites. Additional deliverables of the present project include finding the biomechanisms that prevent the healing cascade to restore the homeostatsis and the knowledge could play critical roles in building limb regeneration strategies.
Thirty male C57BL/6 mice undergo a surgical resection to create artificial segmental femoral defects. The age-and weight matched animals are segregated in three groups during surgery. For Group A, one third of the 30 mice (10 mice) defects are filled with a novel bioabsorbable scaffold imbued with thrombopoietin (TPO). For Group B, the defects of 10 other mice are filled by similar bioabsorbable scaffold imbued with bone morphogenic protein-2 (BMP-2). And, for Group C, the defects of the rest of the 10 mice are filled by the bioabsorbable scaffold imbued with saline as a control. All scaffolds were held in place by a 27 gauge needle. There is another 10 mice (Group D) as control that does not undergo any surgical intervention. The animals are ready to fly 1 week after post-surgery. Twenty mice, 5 from each group (A-D) are housed in the the Rodent Habitat Facility ready to be launched. The rest of the 20 mice are loaded in a separate Rodent Habitat Facility, which is kept on the ground. The mice in both spaceflight and ground are handled in similar conditions and monitored regularly. The mice are euthanized at the end of the space mission (30-45 days).
Post euthanasia, the operated femur and the un-operated femur are fixed in 10% formalin and put in 40ºC cold stowage. Whole blood and organs (brain, heart, kidney, liver, lungs, spleen, ileum and duodenum) are collected and frozen till their delivery to the ground laboratory. It is very critical that the ground based laboratory follow the same schedule of euthanasia, i.e. the time difference from euthanizing one animal to preserving the samples as per the protocol should be similar in the spaceflight and ground.
Upon retrieval from the space mission, the bone characters are evaluated by histopathology study and a range of pan-omics investigations are followed. Heuristic mining algorithm sort and integrate the information to find putative markers associated with the tissue regeneration mediated by microgravity.
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Crew members in orbit experience reduced bone density and muscle mass, a potential consequence of microgravity-induced stress. Yet previous research has also indicated that reduced gravity can promote cell growth, making microgravity a potentially viable environment for tissue regeneration research. This investigation studies the multi-omics aspects of tissue regeneration, which may shed more light on why bone density decreases in microgravity and whether it may be possible to counteract it.
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Serious wounds and broken bones can lead to multiple surgeries, increased infection risks and even loss of limbs; overall it is a financial, physical and psychological burden. Understanding the process of how bones heal improves treatments for patients suffering from various injuries. Results could ultimately lead to tissue regeneration, which would be of great benefit to civilians and military patients who have lost limbs.
Operational Requirements and Protocols
Twenty male C57BL/6 mice to be housed in spaceflight’s Rodent Habitat Facility and same number of age-weight matched mice are housed in ground lab based Rodent Habitat Facility. The animals are routinely monitored in spaceflight and on the ground. Twenty mice are euthanized in the course of 3 days, 5 days at the max. Same schedule is followed in treating the 20 mice housed on the ground. It is preferred to inspect and interchange the video files recording the daily rodent activities in the spaceflight and on the ground. It will be particularly useful to downlink the video files of the euthanization process carried out in spaceflight, which may help in properly timing the same protocol carrying out on earth; and hereby the chances of introducing error due to the sample collections is minimized.
The mice in both spaceflight and on the ground are raised in similar conditions and monitored regularly. The mice are euthanized at end of the space mission. Post euthanasia, whole blood, operated femur and the un-operated femur, and different organs (brain, heart, kidney, liver, lungs, spleen, ileum and duodenum) are collected and preserved until their delivery to the ground laboratory. It is very critical that the earth-based laboratory should follow the same schedule of euthanization, i.e. the time difference from euthanizing one animal to preserving the samples as per the protocol should be same in the spaceflight and on the ground.
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Decadal Survey Recommendations
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