Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Using the sweep and intersect method we were able to create scaffolds within the desired size constraints of 8-‐10mm in diameter, 8-‐10mm in height, and 0.2-‐0.4mm in pore diameter. The peg design seen in Figure 1b in the methods secBon was successful in keeping most of the force off the Agarose layer. The peg design with the Agarose layer has not been empirically tested with the force necessary to insert the scaffold into the subjects body yet; that is a goal for the remainder of the program.
1. Create cylinders in AutoCAD® and successfully print • Using a sweep paKern [figure 1a] we were able to create a laOce-‐
like structure [figure 1c] that was then layered to create the desired height of the scaffold. Once this was complete the intersect command was then used to create scaffold with interconnecBng pores.
2. Test different structural designs’ abiliBes to keep Agarose on when force is applied • We experimented with different ways to disperse the force that is
applied when inserBng the scaffold into the subjects body. • Figure 1b is the “Peg” design we devised so that the pegs rise 2mm
above the Agarose layer so the force is directly to the scaffold instead of the Agarose layer.
3. Create PCL (Polycaprolactone) filament and get to print without breaking
• Use the polycaprolactone pellets and a filament extruder to create the tubular filament necessary for the 3D printer.
• Part of future work 4. Test Strength of PCL printed parts
• Use various stress and strength tests to determine if the scaffold design can handle the forces of everyday wear and tear in the subjects body
• Part of future work 5. Culture Stem cells on printed gra[
• Culture subjects stem cells on the matrix of pores in the scaffold to see if the it will allow for the healthy growth of both bone and carBlage cells
• Part of future work (veterinary laboratory) 6. Test on sheep and dogs
• Once all the previous steps and tests are successfully completed, the scaffolds must then be tested in live subjects to see if they complete the goal of regeneraBng healthy new bone and carBlage when replacing damaged bone and carBlage.
The use of bone gra[s in veterinary medicine is a procedure used for treatment of various types of bone injuries and joint damage. Through veterinary literature, it has become apparent that bone gra[ing has been a part of discussions since the early 1940’s when orthopedic veterinary medicine was first being thought about. [1] A bone gra[ is a transplant of healthy bone in replace of damaged bone. This transplant can occur in the form of an allogra[ or an autogra[. An allogra[ is when the bone is harvested from a cadaver, and an autogra[ refers to bone harvested from the paBent’s body. [2] While these processes do help restore healthy bone and carBlage to the injured areas, both methods have their disadvantages. Autogra[ing is the more favorable of the two because it uses your body’s own Bssue and thus reduces the risk of gra[ rejecBon. However, this method requires extended surgical Bme, and causes increased pain at the harvesBng site and the potenBal for nerve damage at the harvesBng site Allogra[s require less surgical Bme and can reduce the amount of pain by eliminaBng the harvesBng site. However, they do have a greater risk of rejecBon, infecBon, or gra[ morbidity. AddiBonally, allogra[s increase the cost, are not as readily available and in some cases they take longer to fully heal. [3-‐4] UlBmately these two methods can be superior to total joint replacements, especially in younger more acBve subjects. Joint replacement surgeries are o[en used in older paBents to repair arthriBc or severely damaged joints. While this generally increases the overall quality of life and decreases previous joint pain, there are many limitaBons and possible complicaBons it comes with. Most joint replacements last at least 10 years with some of the newer ones lasBng 20-‐25 years. Even then, with conBnued physical acBviBes it can cause wear and tear on the replacement and lead to having to have a new replacement put in. Joint replacements also create a risk for blood clots in paBents. While there are measures taken to prevent this, it is sBll a large risk that comes with the process. Generally joint replacements are a last resort surgery as there is a lot of Bme, dedicaBon, and strain that comes with the extensive rehabilitaBon process. [5]
3D Prin(ng Biodegradable Scaffolds for Use in Regenera(ve Bone Gra:ing Jessica Bramhall1, Samuel Franklin2, Alex Squires1, and Zion Tse1
Abstract
Autogra[s, allogra[s and joint replacements are the current methods used for repairing damaged bone and carBlage in joints. These methods are extensive procedures which cause pain and present post-‐operaBve limitaBons such as the inability to do certain physical acBviBes. Using a 3D printer and stem cell culturing, it is believed that we can print and grow healthy new bone and carBlage to repair damaged joints. Through the use of AutoCAD® (computer-‐aided design so[ware), we have designed a scaffold that meets the desired size restraints and successfully prints on a Solidoodle® 3D printer. This scaffold will be printed and used for strength and stress tesBng, cell bondage tesBng, and Bssue growth tesBng. Upon compleBon of these tests it can be determined if this method of bone and carBlage regeneraBon is a viable opBon for paBents with degeneraBve joint condiBons.
Introduc(on
Aim Results
Summary
Acknowledgements
Methods
1 -‐ College of Engineering, University of Georgia, Athens, GA, United States 2 -‐ College of Veterinary Medicine, University of Georgia, Athens, GA, United States
1. Nunamker, David M., and Frederic W. Rhinelander. "Textbook of Small Animal Orthopaedics." Textbook of Small Animal Orthopaedics. J.B. LippincoK Company, 1985. Web. 18 July 2014.
2. "Bone Gra[s: MedlinePlus." U.S Na;onal Library of Medicine. U.S. NaBonal Library of Medicine, n.d. Web. 18 July 2014. 3. "Pros and Cons of Autogra[ or Allogra[ Use in ACL ReconstrucBon." Desio Sports Medicine RSS. N.p., n.d. Web. 18 July 2014. 4. "Autogra[: The PaBent's Own Bone." Spine-‐health. N.p., n.d. Web. 18 July 2014. 5. "Weighing the Pros and Cons of Knee Replacement Surgery: Special Reports."Johns Hopkins Health Alerts. N.p., n.d. Web. 18 July 2014.
References
1. Research reported in this publicaBon was supported by the NaBonal Science FoundaBon with the project Btle REU Site: Interdisciplinary Research Experiences in Nanotechnology and Biomedicine, under award number EEC-‐1359095.
2. Dr. Mao 3. Dr. Arnold 4. Medical RoboBcs Lab at UGA 5. Jason Locklin
HarvesBng site for bone gra[
• Create biodegradable scaffolds that can be used for stress tesBng, cell bondage tesBng, and Bssue growth tesBng.
• Develop a structural design that will keep Agarose, a hydrophilic material,
aKached to Polycaprolactone (PCL), a hydrophobic material, while the necessary force for inserBon is exerted onto the scaffold.
Figure 1a Figure 1c Figure 1b
UGA
(Le[) Final printed peg scaffold (Top Le[) Side view of sweep method scaffold with 8.4mm height, 10mm diameter and 0.6mm pore (Top Right) Top view of scaffold with 0.6mm pore (red box) (Right) Final printed peg scaffold with approximately a 2mm layer of Agarose on top
In an aKempt to find a different method for repairing damaged bone and carBlage in joints we have used 3D prinBng to create biodegradable scaffolds that can then be used for bone and carBlage gra[ing. Using the sweep method, we were able to create a scaffold that is 8.4mm tall, 10mm in diameter, with 0.6mm pores and a taper of 4°. QualitaBvely, the scaffold holds up well when force is applied to it, and quanBtaBve tesBng is planned to support the results. Further strength and stress tesBng will be conducted on the scaffold in the future once it is printed with the biodegradable material. The peg design in Figure 1b successfully molded with the Agarose when placed in the well with it. The producBon of the polycaprolactone (PCL) filament and prinBng the scaffolds using this material are the next tasks in line. Once the scaffold is successfully printed with PCL, full strength and stress tesBng can be conducted and the final steps in the method secBon can be carried out. These tests will determine if 3D prinBng biodegradable scaffolds for use in joint repair is a viable opBon for subjects with degeneraBve joint condiBons. If this is successful the same process could then be used for joint replacements. This would eliminate the use of plasBcs and metals in the subject and provide the ability to grow a healthy new joint.
Figure 2d
Figure 2c
Figure 2a
Figure 2b