"What we're making can replace current patches in an operation that surgeons are already familiar with and that has a very high short- and medium-term success rate, but with long-term complications," he said.
A better scaffold would have to perform many functions perfectly. It must be strong enough to withstand the pressures delivered by a beating heart yet flexible enough to expand and contract; porous enough to allow new heart cells to migrate, make connections and excrete their own natural scaffold to replace the patch; and tough enough to handle sutures but still be able to biodegrade over just the right amount of time for natural tissue to take over.
The sandwich the researchers created seems to fill the bill on all counts. In the middle is a self-assembled polycaprolactone (PCL) polymer that hardens into a tough but stretchable ribbon. Mixing two types of PCL with different molecular weights allows tiny pores to form along the rough surface. The "bread" is a hydrogel made from a 50/50 mixture of gelatin and chitosan, a widely used material made from the shells of crustaceans like shrimp.
Heart cells cultured on the hydrogel surface were able to thrive and formed networks and ultimately beat. Though cells could not attach to the surface or pass through the pores of the PCL, the pores do allow nutrients to migrate from one side to the other, Jacot said. They also allow the hydrogel to hold on to the PCL core.
The lab tested the biodegradable qualities of the PCL and found that over 50 days, about 15 percent dispersed, leaving a ragged sheet. "It degrades in water," Jacot said. "If it's in the body, it will degrade, but it will be very slow, over the course of months.
"It should be stable for long enough th
|Contact: David Ruth|