{"671309":{"#nid":"671309","#data":{"type":"news","title":"Hollister Lab Develops 3D Printing for Soft Tissue Engineering","body":[{"value":"\u003Cp\u003EThere are young children celebrating the holidays this year with their families, thanks to the 3D-printed medical devices created in the lab of\u0026nbsp;\u003Ca href=\u0022https:\/\/hollisterlab.bme.gatech.edu\/\u0022\u003EGeorgia Tech researcher Scott Hollister\u003C\/a\u003E. For more than 10 years, Hollister and his collaborators have developed lifesaving, patient-specific airway splints for babies with rare birth defects.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThese personalized Airway Support Devices are made of a biocompatible polyester called\u0026nbsp;polycaprolactone (PCL), which has the advantage of being approved by the Food and Drug Administration. Researchers use selective laser sintering to heat the powdered polyester, which binds together as a solid structure. Devices made of PCL have a great safety record when implanted into patients.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EUnfortunately, PCL has the disadvantage of having relatively stiff and linear mechanical properties, which means this promising biomaterial has yet to be applied functionally to some other critical biomedical needs, such as soft tissue engineering. How do you make a firm thermoplastic into something flexible, and possibly capable of growing with the patient? Hollister\u2019s lab has figured out how.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201c3D auxetic design,\u201d said Jeong Hun Park, a research scientist in Hollister\u2019s lab who led the team\u2019s recent study demonstrating the successful\u0026nbsp;\u003Ca href=\u0022https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/adfm.202215220\u0022\u003E3D printing of PCL for soft tissue engineering\u003C\/a\u003E. An auxetic material, unlike typical common elastics, has a negative Poisson\u2019s ratio. That means if you stretch an auxetic material longitudinally it will also expand in the lateral direction, whereas most materials will get thinner laterally (because they have a positive Poisson\u2019s ratio).\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESo, an auxetic structure can expand in both directions, which is useful when considering biomedical applications for humans, whose bodies and parts can change in size and shape over time and comprise many different textures and densities. Hollister\u2019s team set out to give usually firm PCL some new auxetic properties.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cAlthough the mechanical properties and behavior of the 3D structure depend on the inherent properties of the base material \u2014 in this case, PCL \u2014 it can also be significantly tuned through internal architecture design,\u201d explained Park.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EPark guided the design of 3D-printed structures made up of tiny struts, arranged at right angles \u2014 imagine the bones of very tiny skyscrapers. The team began by creating cube-shaped structures first, to test the auxetic design\u2019s flexibility, strength, and permeability.\u003C\/p\u003E\r\n\r\n\u003Ch4\u003E\u003Cstrong\u003EFlexible Behavior\u003C\/strong\u003E\u003C\/h4\u003E\r\n\r\n\u003Cp\u003EBasically, an auxetic material is a network structure designed by assembling unit cells. These unit cells consist of struts and their intersecting joints, which are an important aspect of an auxetic device\u2019s behavior. The rotation of those intersecting joints within the network, under compression or extension, causes negative Poisson\u2019s behavior. It also enables advanced performance for a printed device, including impact energy absorption, indentation resistance, and high flexibility.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cWhen you look at the numbers, based on Jeong Hun\u2019s work, the new structure is about 300 times more flexible than the typical solid structure we make out of PCL in our lab,\u201d said Hollister, professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, where he also holds the Patsy and Alan Dorris Chair in Pediatric Technology and serves as the department\u2019s associate chair for translational research.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe combination of flexibility and strength in a device is particularly important here, Park said, because the ultimate goal of the research is to \u201capply this structure to develop a breast reconstruction implant that has comparable biomechanical properties to native breast tissue. Currently, we don\u2019t have a biodegradable breast implantation option in the clinical setting.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003EHe explained that these biodegradable breast reconstruction implants serve as a kind of scaffold. The idea is, the biocompatible material (PCL) eventually degrades and is absorbed into the body, while maintaining similar mechanical properties to native breast tissue.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cWe expect that native tissue will be first infiltrated into the pores of the biodegradable implant,\u201d Park said. \u201cTissue volume will then increase within the implant as it degrades and eventually the device itself is replaced with the tissue after complete degradation of the implant.\u201d\u003C\/p\u003E\r\n\r\n\u003Ch4\u003EExpanding the Cellular Network\u003C\/h4\u003E\r\n\r\n\u003Cp\u003EEssentially, the 3D-printed breast implant is designed to provide reconstructive support while also facilitating the growth of new tissue.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe space between those tiny struts makes all the difference for the larger device, giving it a softness and pliability that would have been impossible otherwise. Those spaces eventually can be filled with hydrogel that will help foster cell and tissue growth.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe team\u2019s architected auxetics also include the design of inner voids and spaces inside the struts, creating a kind of microporosity that enables the mass transport of oxygen, nutrients, and metabolites to nurture the expansion and growth of a cellular network.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EPark is working with Emory surgeon\u0026nbsp;\u003Ca href=\u0022https:\/\/winshipcancer.emory.edu\/bios\/faculty\/cheng-angela.html\u0022\u003EAngela Cheng\u003C\/a\u003E\u0026nbsp;in submitting a grant for further research and testing of the breast implant. And the team already is adapting the technology for other applications. One of the collaborators in this research, for example, is\u0026nbsp;\u003Ca href=\u0022https:\/\/www.davislab.org\/michael-e-davis-phd\u0022\u003EMike Davis\u003C\/a\u003E, whose lab at Emory is focused on cardiac regeneration.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u201cBecause of the great flexibility, they\u2019re using it to reconstruct infarcted or necrotic myocardial tissue,\u201d Hollister said.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EAnd Park has developed an auxetic version of the pediatric tracheal splint. \u201cThe advantage there is, with this design, it can expand in two directions,\u201d he said. \u201cSo, as young patients grow, the new device will grow with them.\u201d\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Ca href=\u0022https:\/\/www.youtube.com\/watch?v=HvaMQViusGs\u0022\u003E\u003Cem\u003E\u003Cstrong\u003EVideo Demonstration of Auxetic Compression\u003C\/strong\u003E\u003C\/em\u003E\u003C\/a\u003E\u003C\/p\u003E\r\n","summary":"","format":"limited_html"}],"field_subtitle":[{"value":"Researchers use architected auxetics to achieve 300 times more flexibility in new 3D printing design"}],"field_summary":[{"value":"\u003Cp\u003EResearchers use architected auxetics to achieve 300 times more flexibility in new 3D printing design\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers use architected auxetics to achieve 300 times more flexibility in new 3D printing design."}],"uid":"28153","created_gmt":"2023-11-30 13:01:42","changed_gmt":"2024-01-04 14:14:26","author":"Jerry Grillo","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2023-11-30T00:00:00-05:00","iso_date":"2023-11-30T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"672478":{"id":"672478","type":"image","title":"JeongHun Park","body":"\u003Cp\u003EResearch scientist JeongHun Park\u003C\/p\u003E\r\n","created":"1701348958","gmt_created":"2023-11-30 12:55:58","changed":"1701349053","gmt_changed":"2023-11-30 12:57:33","alt":"Research scientist JeongHun Park","file":{"fid":"255719","name":"JeongHun.jpg","image_path":"\/sites\/default\/files\/2023\/11\/30\/JeongHun.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/2023\/11\/30\/JeongHun.jpg","mime":"image\/jpeg","size":6978616,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/2023\/11\/30\/JeongHun.jpg?itok=jIi7SJ8a"}}},"media_ids":["672478"],"groups":[{"id":"1292","name":"Parker H. Petit Institute for Bioengineering and Bioscience (IBB)"},{"id":"1188","name":"Research Horizons"}],"categories":[],"keywords":[{"id":"187423","name":"go-bio"},{"id":"187915","name":"go-researchnews"},{"id":"13351","name":"3d printing"},{"id":"177006","name":"biomedical device"},{"id":"191525","name":"Scott Hollister"}],"core_research_areas":[{"id":"39441","name":"Bioengineering and Bioscience"}],"news_room_topics":[{"id":"71891","name":"Health and Medicine"},{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EWriter: \u003Ca href=\u0022mailto:jerry.grillo@ibb.gatech.edu\u0022\u003EJerry Grillo\u003C\/a\u003E\u003C\/p\u003E\r\n","format":"limited_html"}],"email":["jerry.grillo@ibb.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}