10.17.17 // I made osteoclasts this week! I plated mouse macrophages, and using various treatments (including positive control RANKL), I got some beautiful chubby boys. Osteoclasts form when their precursors (monocytes) fuse together into giant multi-nucleated cells. Osteoclasts are responsible for resorbing or breaking-down bone, and their increased numbers and activities can cause the bone-lysing events of breast cancer bone metastasis (which is why I’m playing around with them). 

Bone density vocab
  • 骨粗鬆症 こつそしょうしょう osteoporosis
  • 骨密度 こつみつど bone density; bone mineral density
  • 外来 がいらい outpatient
  • 破骨細胞 はこつさいぼう osteoclast
  • 骨芽細胞 こつがさいぼう osteoblast
  • DXA法 デキサほう DXA scan; dual-energy X-ray absorptiometry
  • 照射 しょうしゃ radiation; irradiation
  • 透過度 とうかど transmittance
  • 断面図 だんめんず cross-section drawing; profile
  • 脆弱性骨折 ぜいじゃくせいこっせつ low-trauma fracture
  • 骨代謝 こつたいしゃ bone metabolism; bone turnover
  • 閉経後 へいけいご postmenopause
  • 骨質量 こつしつりょう bone mass
Space Station Science: Biological Research

Each month, we highlight a different research topic on the International Space Station. In August, our focus is biological research. Learning how spaceflight affects living organisms will help us understand potential health risks related to humans on long duration missions, including our journey to Mars.

Cells, microbes, animals and plants are affected by microgravity, and studying the processes involved in adaptation to spaceflight increases our fundamental understanding of biological processes on Earth. Results on Earth from biological research in space include the development of new medications, improved agriculture, advancements in tissue engineering and regeneration, and more. 

Take a look at a few of the biological research experiments performed on space station:

Biomolecule Sequencer

Living organisms contain DNA, and sequencing DNA is a powerful way to understand how they respond to changing environments. The Biomolecule Sequencer experiment hopes to demonstrate (for the first time) that DNA sequencing is feasible in an orbiting spacecraft. Why? A space-based DNA sequencer could identify microbes, diagnose diseases and understand crew member health, and potentially help detect DNA- based life elsewhere in the solar system.


Yes, ant-stronauts…as in ants in space. These types of studies provide insights into how ants answer collective search problems. Watching how the colony adapts as a unit in the quest for resources in extreme environments, like space, provides data that can be used to build algorithms with varied applications. Understanding how ants search in different conditions could have applications for robotics.


The TAGES experiment (Transgenic Arabidopsis Gene Expression System) looks to see how microgravity impacts the growth of plant roots. Fluorescent markers placed on the plant’s genes allow scientists to study root development of Arabidopsis (a cress plant) grown on the space station. Evidence shows that directional light in microgravity skews root growth to the right, rather than straight down from the light source. Root growth patters on station mimic that of plants grown at at 45% degree angle on Earth. Space flight appears to slow the rate of the plant’s early growth as well.

Heart Cells

Spaceflight can cause a suite of negative health effects, which become more problematic as crew members stay in orbit for long periods of time. Effects of Microgravity on Stem Cell-Derived Cardiomycytes (Heart Cells) studies the human heart, specifically how heart muscle tissue contracts, grows and changes in microgravity. Understanding how heart muscle cells change in space improves efforts for studying disease, screening drugs and conducting cell replacement therapy for future space missions.

Medaka Fish

Chew on these results…Jaw bones of Japanese Medaka fish in microgravity show decreased mineral density and increased volume of osteoclasts, cells that break down bone tissue. Results from this study improve our understanding of the mechanisms behind bone density and organ tissue changes in space.

These experiments, and many others, emphasize the importance of biological research on the space station. Understanding the potential health effects for crew members in microgravity will help us develop preventatives and countermeasures.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Lack of estrogen causes a decrease in osteoprotegerin.

Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor (OCIF), is a cytokine and a member of the tumor necrosis factor (TNF) receptor superfamily.

Osteoprotegerin inhibits the differentiation of macrophages into osteoclasts and also regulates the resorption of osteoclasts.
Mnemonic: Osteoprotegerin protects bone (By preventing macrophage differentiation into osteoclasts.)

Osteoprotegerin, a RANK homolog, works by binding to the RANK-ligand on Osteoblast/Stromal cells, thus blocking the RANK-RANK lingand interaction between Osteoblast/Stromal cells and Osteoclast precursors. This has the effect of inhibiting the differentiation of the Osteoclast Precursor into a mature Osteoclast.
Mnemonic: Osteoprotegerin ranks high in protecting bones.

So, estrogen kinda inhibits the osteoclasts which causes osteoporosis is the moral of the story?


Extra: Recombinant human osteoprotegerin specifically acts on bone, increasing bone mineral density and bone volume. Osteoprotegerin has been used experimentally to decrease bone resorption in women with postmenopausal osteoporosis and in patients with lytic bone metastases.

That’s all!


Boney remodeling is a chronic process of replacement with minimal change in the gross shape of the bone structure. Osteoblasts and osteoclasts together are referred to as bone remodeling units. They work in concert together, coordinated via paracrine signaling by the osteoblasts. The constant remodeling allows for calcium homeostasis and the repair of microscopic daily stressors. The histology slide show demonstrates bone remodeling with osteoclasts resorbing one side of a bony trabecula and osteoblasts depositing new bone on the other side.

What’s On Board the Next SpaceX Cargo Launch?

Cargo and supplies are scheduled to launch to the International Space Station on Monday, July 18 at 12:45 a.m. EDT. The SpaceX Dragon cargo spacecraft will liftoff from our Kennedy Space Center in Florida.

Among the arriving cargo is the first of two international docking adapters, which will allow commercial spacecraft to dock to the station when transporting astronauts in the near future as part of our Commercial Crew Program.

This metallic ring, big enough for astronauts and cargo to fit through represents the first on-orbit element built to the docking measurements that are standardized for all the spacecraft builders across the world.

Its first users are expected to be the Boeing Starliner and SpaceX Crew Dragon spacecraft, which are both now in development.

What About the Science?!

Experiments launching to the station range from research into the effects of microgravity on the human body, to regulating temperature on spacecraft. Take a look at a few:

A Space-based DNA Sequencer

DNA testing aboard the space station typically requires collecting samples and sending them back to Earth to be analyzed. Our Biomolecule Sequencer Investigation will test a new device that will allow DNA sequencing in space for the first time! The samples in this first test will be DNA from a virus, a bacteria and a mouse.

How big is it? Picture your smartphone…then cut it in half. This miniature device has the potential to identify microbes, diagnose diseases and evaluate crew member health, and even help detect DNA-based life elsewhere in the solar system.


OsteoOmics is an experiment that will investigate the molecular mechanisms that dictate bone loss in microgravity. It does this by examining osteoblasts, which form bone; and osteoclasts, which dissolves bone. New ground-based studies are using magnetic levitation equipment to simulate gravity-related changes. This experiment hopes to validate whether this method accurately simulates the free-fall conditions of microgravity.

Results from this study could lead to better preventative care or therapeutic treatments for people suffering bone loss, both on Earth and in space!

Heart Cells Experiment

The goals of the Effects of Microgravity on Stem Cell-Derived Heart Cells (Heart Cells) investigation include increasing the understanding of the effects of microgravity on heart function, the improvement of heart disease modeling capabilities and the development of appropriate methods for cell therapy for people with heart disease on Earth.

Phase Change Material Heat Exchanger (PCM HX)

The goal of the Phase Change Material Heat Exchanger (PCM HX) project is to regulate internal spacecraft temperatures. Inside this device, we’re testing the freezing and thawing of material in an attempt to regulate temperature on a spacecraft. This phase-changing material (PCM) can be melted and solidified at certain high heat temperatures to store and release large amounts of energy.

Watch Launch!

Live coverage of the SpaceX launch will be available starting at 11:30 p.m. EDT on Sunday, July 17 via NASA Television

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Osteoclasts (shown) resorb bone over a period of weeks, and are especially active during periods of rapid remodeling (eg, after menopause). Because osteoclasts work faster than osteoblasts, the rate of bone loss may outpace the rate of bone production. During these periods, the newly produced bone is at increased risk for fracture because it is less densely mineralized, collagen has not matured, and resorption sites are temporarily unfilled.