One of the most rigorously researched problems in tissue engineering — creating organs in the lab — may well find clues in the way leaves grow, a team of engineers at the Indian Institute of Science suggests in a paper.
Leaves, with the baffling array of shapes and sizes they can morph into, could, in the future, be tailored to match a targeted form, the team shows, using mathematical modelling.
And “if successful, this approach may be useful to control the shapes of organs grown ex vivo [outside the body] in tissue engineering,” says a paper presented at the International Conference on Engineering and Applied Sciences Optimization in Kos Island, Greece, this week.
While science has a fairly good grasp on how leaves develop into complex and varied structures, little work has been done on controlling and influencing leaf shapes to obtain specific, prerequisite forms. This is precisely the “inverse problem” the team is working on at the Mechanical Engineering department using geometry and computational modelling.
“We are working backwards. So we first understand growth rates of different leaf tissues. For instance cells closest to the petiole [stem] grow the fastest. We then use computational models to simulate growth rates needed for a desired form,” said co-author G.K. Ananthasuresh, professor at the department.
Leaves curl and twist and warp from ‘residual stress’ in cells and tissues as they compete to grow within a finite space. And it is when tissues ‘go out of plane’ that they acquire the shapes they do. “Our goal is to manipulate residual stress and control it to arrive at a specific form,” he says.
To compute the disparate growth rate the team uses a ‘mesh’ grid to break up the leaf into smaller segments and analyse displacement and internal stress more closely.
However, unlike leaves, the growth of human organs have external influences. “Organs grow in a circumscribed space, influencing their form. Leaves therefore are easier to study and control.”
The next logical step would be to identify genes and use genetic manipulation to create living models of leaves in shapes we want, he says, adding he might first experiment with creating some tea ware from leaves. “We might just start by growing cups and saucers and spoons on trees.”
