Stem-cell Laden Implants for Cartilage Defect Repair

Three dimensional printing of polymers can be done through a moving orifice (e.g. fused deposition) or by photopolymerizing a liquid (e.g. stereolithography). In 2013, we developed a new form of stereolithographic printer using an image projector, a PDMS coated window and a moving platform, as shown below. This system can print significantly faster than the traditional scanning laser and recoating blade. We exploit this speed to print at very small (~micron) scale and very soft (KPa to MPa) polymers that are used in regenerative medicine. We are currently printing implants for defects of knee cartilage that may provide a cure to osteoarthritis.

The team

  • Camila Uzcategui
  • Archish Muralidharan
  • Johnny Hergert

Cami with an SLA printer

Archish with an SLA printer

Showing off (sometimes we print things that are just for fun)

Eiffel Tower print inside vial

A printed Eiffel Tower suspended in ethanol in a vial. The dark blob on the left is a finger-tip.

X-ray tomography videos and of the printed Eiffel tower held by a finger

Learn more

  • A. C. Uzcategui, A. Muralidharan, V. L. Ferguson, S. J. Bryant, and R. R. McLeod, “,” Advanced Engineering Materials 2018, 1800876, 2018. .
  • Elizabeth A Aisenbrey, Andrew Tomaschke, Eric Kleinjan, Archish Muralidharan, Cecilia Pascual-Garrido, Robert R McLeod, Virginia L. Ferguson, Stephanie J Bryant, “,”Macromol. Biosci.2017, 1700267, 2017
  • Callie Fiedler,,University of Colorado, 2017.
  • C. I. Fiedler, E. A. Aisenbrey, J.A. Wahlquist, C. M. Heveran, V. L. Ferguson, S. J. Bryant, and R. R. McLeod, “,” Soft Matter12, 9095 – 9104,2016
  • A.C. Urness, E.D. Moore, K.K. Kamysiak, M.C Cole and R.R McLeod,,” Light: Science & Applications2(Nature Publishing Group) , e56, 2013
  • A. Linnenberger, M. I. Bodine, C. Fiedler, J. J. Roberts, S. C. Skaalure, S. J. Bryant M. Cole, R. R. McLeod,,” Optics Express21, 10269-10277, 2013

This work has been generously funded by

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NIH

Sample results

Stereolithography apparatus

Layout of a stereolithographic printer. 405 nm light is patterned into a ~megapixel image by a DMD spatial light modulator and projected through a glass window into the exposure chamber. The interior of this window is coated with an oxygen permeable membrane that inhibits polymerization, preventing adhesion of the polymer to the window. As the platform moves, the image is changed, printing a 3D solid part from the liquid resin.

SEM of printed scaffold

SEM of a hydrated PEG acrylate scaffold printed in our custom stereolithography system. The stiff scaffoldis subsequently back filled with a soft hydrogel containing mesenchymal stem cells. This is implanted in a cartilage defectto regrow bone and cartilage, with the goal of preventing osteoarthritis.

Printed implant in OC defect

Focal chondral defect in an osteochondral plugexplanted from the trochlear groove of porcine knees, thenfilled with the hybrid scaffold. The photograph wastaken immediately after filling and prior to culture.