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). 听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. 听This system can print significantly faster than the traditional scanning laser and recoating blade. 听We exploit this speed to print at very small (~micron) scale and very soft (KPa to MPa) polymers that are used in regenerative medicine. 听We are currently printing implants for defects of knee cartilage that may provide a cure to osteoarthritis. 听

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, 鈥,鈥 Advanced Engineering Materials 2018, 1800876, 2018. 听.
  • Elizabeth A Aisenbrey, Andrew Tomaschke, Eric Kleinjan, Archish Muralidharan, Cecilia Pascual-Garrido, Robert R McLeod, Virginia L. Ferguson, Stephanie J Bryant, 鈥,鈥澨齅acromol. Biosci.听2017, 1700267, 2017
  • Callie Fiedler,听,听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, 鈥,鈥 Soft Matter听12, 9095 鈥 9104,听2016
  • A.C. Urness, E.D. Moore, K.K. Kamysiak, M.C Cole and R.R McLeod,听,鈥 Light: Science & Applications听2听(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,,鈥 Optics Express听21, 10269-10277, 2013

This work has been generously funded by

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NSF Logo
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NIH

Sample results

Stereolithography apparatus

Layout of a stereolithographic printer. 听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. 听The interior of this window is coated with an oxygen permeable membrane that inhibits polymerization, preventing adhesion of the polymer to the window. 听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. 听The stiff scaffold听is subsequently back filled with a soft hydrogel containing mesenchymal stem cells. 听This is implanted in a cartilage defect听to regrow bone and cartilage, with the goal of preventing osteoarthritis.

Printed implant in OC defect

Focal chondral defect in an osteochondral plug听explanted from the trochlear groove of porcine knees, then听filled with the hybrid scaffold. The photograph was听taken immediately after filling and prior to culture.