A Pittsburgh-based research team has created and used an innovative ink-jet system to print "bio-ink" patterns that direct muscle-derived stem cells from adult mice to differentiate into both muscle cells and bone cells. Technology could revolutionize the design of replacement body tissues and one day benefit millions of people whose tissues are damaged from a variety of conditions, including fatal genetic diseases like Duchenne Muscular Dystrophy (DMD), wear and tear associated with aging joints, accidental trauma, and joint deterioration due to autoimmune disorders.

"Previously, researchers have been limited to directing stem cells to differentiate toward multiple lineages in separate culture vessels. This is not how the body works: the body is one vessel in which multiple tissues are patterned and formed. The ink-jet printing technology allows us to precisely engineer multiple unique microenvironments by patterning bio-inks that could promote differentiation towards multiple lineages simultaneously," explained Phil Campbell, research professor at Carnegie Mellon's Institute for Complex Engineered Systems.

"Controlling what types of cells differentiate from stem cells and gaining spatial control of stem cell differentiation are important capabilities if researchers are to engineer replacement tissues that might be used in treating disease, trauma or genetic abnormalities," said Lee Weiss, research professor at Carnegie Mellon's Robotics Institute.

The custom-built ink-jet printer, developed at Carnegie Mellon's Robotics Institute, can deposit and immobilize growth factors in virtually any design, pattern or concentration, laying down patterns on native extracellular matrix-coated slides (such as fibrin). These slides are then placed in culture dishes and topped with muscle-derived stem cells (MDSCs). Based on pattern, dose or factor printed by the ink-jet, the MDSCs can be directed to differentiate down various cell-fate differentiation pathways (e.g. bone- or muscle-like).

The long-term promise of this new technology could be the tailoring of tissue-engineered regenerative therapies. In preparation for preclinical studies, the Pittsburgh researchers are combining the versatile ink-jet system with advanced real-time live cell image analysis developed at the Robotics Institute and Molecular Biosensor and Imaging Center to further understand how stem cells differentiate into bone, muscle and other cell types.