The enormous potential to transform regenerative medicine and current bottlenecks to progress. One question I am often asked when interacting with the general public is, “how close are we to being able to 3D bioprint human organs”? This question has become increasingly relevant as 3D bioprinting technologies continue to advance to the point where technology previously only featured in science fiction shows is on the horizon. For example, the television show Westworld – based on the Michael Crichton novel, envisions a world where people, horses, and an assortment of other living things can be produced using only their fictional 3D printing technologies. Interestingly, we already have 3D bioprinters capable of generating tissue substitutes with the end goal of transplantation. Dr. Axel Guenther’s group at the University of Toronto has been hard at work developing a novel, handheld 3D bioprinting system for generating skin tissues that are not only directly implantable but also able to promote skin regeneration and scar reduction in trauma care (Figure 1). This printer has already been evaluated in animal models and is expected to be seen in a clinical setting within 5 years. You can read more about Dr. Guenther’s group here.

However, skin is a relatively simple organ to reproduce through 3D bioprinting in terms of its cellular composition and structure- not all structures are mechanically stable once printed. Therefore, other research groups are currently developing tools to generate more complex organs – such as heart replacements or artificial pancreases. Dr. Adam Feinberg’s group at Carnegie Mellon University and his start-up company – FluidForm – have done extensive work in developing tools for 3D printing more complex structures- using their novel technique freeform reversible embedding of suspended hydrogels (FRESH). Using FRESH (Figure 2), printed structures are supported until they are fully cured- allowing even hearts and heart valves to be printed. This technology was recently reviewed by their group as detailed here. Another team at the Vancouver based biotechnology company, Aspect Biosystems, is currently running several major pre-clinical programs working towards generating the necessary data for translating the efficacy of 3D bioprinted tissue models for clinical translation. More about their research efforts can be read here.

One major challenge in engineering implantable organs is figuring out how to generate the number of cells required to produce such engineered tissue, while also being able to print stable structures that will accurately mimic the function of the target tissue. Typical tissues found in the body have high cell densities and thus printing truly mimetic organs requires millions of cells to be cultured prior to starting the printing process. The degree of complexity found in the target tissue will also dictate the difficulty of the process needed to replicate that structure. As stated above, bioprinting skin replacements then present a lower bar to clinical translation compared to more complex organs such as the heart. Stem cells serve as an important tool for bioprinting as these cells can both self-replicate to produce more stem cells as well as differentiate into mature phenotypes. Thus, the use of bioreactors- systems designed to grow large quantities of cells- will play an important role in enabling the use of 3D bioprinting for the generation of replacement organs. These systems contain monitoring systems to ensure cell survival and function are maximized during the expansion process and are produced by companies like Pall and Sartorius.  

The tissues found in our body are nourished and maintained by a system of blood vessels known as vasculature. Being able to replicate this network in a bioprinted tissue can be challenging due to the requirements to maintain functional blood vessels while also ensuring proper integration into the tissues. Prellis Biologics has developed a novel laser-based 3D printer that generates high-resolution structures that resemble the different types of vasculature found in the tissues of the body- while also being cell and transplant compatible. While these structures are not yet of sufficient size to enable replication of larger organs – this technology represents an important first step towards generating vascularized tissues. 

Similar technologies have been developed by Dr. Jordan Miller (Rice University and Volumetric Bio) who has developed a 3D bioprinter that uses stereolithography to quickly and consistently generate functional blood vessels. This technology is also compatible with the use of other bioprinters when generating 3D bioprinted tissue models. 

A final challenge when 3D bioprinting tissues for human implantation, is the development and validation of bioinks that do not use animal-derived products, as these materials can trigger an immune response. My company- Axolotl Biosciences has developed a novel bioink that does not rely on such components while also being compatible with any patient’s cells- further minimizing the risks associated with transplantation (Figure 3). Our novel bioinks support superior levels of stem cell survival (>90%) and differentiation compared to other commercially available inks. Our recent Advanced NanoBiomed Research publication demonstrates how our microsphere-laden inks could generate responsive neural tissues from stem cells. You can learn more about Axolotl Biosciences on our website.

Overall, while there are several major challenges to be addressed, thanks to the innovative solutions of research groups all over the world- the future is quite promising for the development of 3D bioprinted tissues for transplantation.

About the Author:

Dr. Willerth holds a Canada Research Chair in Biomedical Engineering at the University of Victoria where she has dual appointments in the Department of Mechanical Engineering and the Division of Medical Sciences as a Full Professor. She runs an active research group that engineers tissues from stem cells and is currently starting a company to sell bioinks for engineering neural tissues. She serves as the Acting Director for the Centre for Biomedical Research at the University of Victoria and on the steering committee of the B.C. Regenerative Medicine Initiative. Her honors include being named the 2018 REACH award winner for Excellence in Undergraduate Research-inspired Teaching, a Woman of Innovation in 2017, one of the 2015 Young Innovators in Cellular and Biological Engineering and a “Star in Global Health” by Grand Challenges Canada in 2014.  She spent Fall of 2016 on sabbatical at the Wisconsin Institute for Discovery supported by the International Collaboration on Repair Discoveries International Travel Award where she wrote her book “Engineering neural tissue using stem cells” published by Academic Press. She completed her postdoctoral work at the University of California-Berkeley after receiving her Ph.D. in Biomedical Engineering from Washington University. Her undergraduate degrees were in Biology and Chemical Engineering from the Massachusetts Institute of Technology.

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The post Translating 3D Bioprinting for Clinical Applications appeared first on 3DHeals.

Glioblastoma is one of the most common and deadliest forms of brain cancer in adults. It results from mutations in cells called astrocytes, which normally play an important role in maintaining the function of the brain. These mutations turn these supportive cells into cancerous cells that aggressively invade tissue while continuing to expand, causing significant damage to the brain and its function.  The deeply invasive nature of glioblastoma tumors, it often recurs after the initial treatment regime that consists of tumor removal followed by either chemotherapy using temozolomide or radiotherapy.

As it currently stands, there is a clear lack of effective treatments to eradicate this type of cancer. Glioblastoma samples were taken from patients who also exhibit significant variability, which dictates how they will respond to potential treatments. The heterogeneous nature of cancer, including glioblastoma, makes it difficult to find effective treatments and the complex behavior and microenvironment associated with this type of the disease are hard to replicate in vitro. The standard paradigms for evaluating potential treatments for glioblastoma often require screening drugs against glioblastoma cells cultured on 2D tissue culture plates. These conditions do not accurately represent the complexity of the in vivo environment as they do not recapitulate the effect of the vasculature and the associated immune cells nor do they allow the cells to migrate in three dimensions as they would in the body. Another commonly used strategy is to transplant human glioblastoma derived tumor cells into animal models for screening potential treatments. These models have additional issues that include variability in tumor engraftment and the need to implant these cells into immunocompromised mice to ensure cell survival post-implantation.

As mentioned earlier, the role of the 3D microenvironment has a large impact on how glioblastoma cells behave and thus there exists a need to develop improved 3D models for studying the behavior of these cells. 3D bioprinting has the potential to generate such complex models as detailed in a recent commentary (1). For example, our group used the RX1 bioprinter from Aspect Biosystems to generate a novel 3D model of glioblastoma (2). Here we used our unique fibrin-based bioink containing U87 human glioblastoma cells to generate ring-shaped constructs based on the specifications present in our initial computer-aided design (CAD) file. The resulting constructs exhibited high levels of cell viability and the cells seeded inside formed tumor spheroids. Additional analysis showed that the cells in our bioprinted constructs expressed higher levels of the glioblastoma stem cell marker CD133 as well as doublecortin which is also upregulated in glioblastoma cells, that suggests these cells are more tumor-like in our 3D system in comparison with 2D culture. Additionally, our lab recently discovered a novel small molecule cocktail for reprogramming human glioblastoma cells in non-proliferating neurons when cultured on 2D surfaces and inhibiting the formation of cancer spheroids in suspension culture (3). However, the effects of this novel treatment were less profound when tested on our novel 3D bioprinted glioblastoma model. Another recent study also illustrated how complex models of glioblastoma can be produced using 3D bioprinting (4). They used a prototype of an extrusion bioprinting system developed by Renishaw to generate constructs from a bioink consisting of alginate modified with the peptide sequence RGD containing different types of glioblastoma cells along with immune cells into disc-shaped constructs. They then demonstrated that the 3D cancer models showed greater resistance to treatment with cisplatin and temozolomide when compared to 2D models – further demonstrating the potential of 3D bioprinting to generate more relevant, humanized models for drug screening. Another recent study published in Cell demonstrated how glioblastoma organoids – mini tissues formed from stem cells that reproduce certain biological functions – could be generated from patient-derived samples using defined conditions and these organoids exhibited the characteristics of the tumors from which they were derived (5).  This technology could potentially be combined with 3D printing to generate patient-specific models for drug screening.  Overall, as 3D bioprinting technology advances, including the ability to generate complex constructs using advanced bioactive inks that support cell survival, so will the development of such tissue models for drug screening applications.

References

1.         Liu T, Delavaux C, Zhang YS. 3D bioprinting for oncology applications. Journal of 3D printing in medicine. 2019(0).

2.         Lee C, Abelseth E, de la Vega L, Willerth S. Bioprinting a novel glioblastoma tumor model using a fibrin-based bioink for drug screening. Materials Today Chemistry. 2019;12:78-84.

3.         Lee C, Robinson M, Willerth SM. Direct Reprogramming of Glioblastoma Cells into Neurons Using Small Molecules. ACS chemical neuroscience. 2018.

4.         Hermida MA, Kumar JD, Schwarz D, Laverty KG, Di Bartolo A, Ardron M, et al. Three dimensional in vitro models of cancer: Bioprinting multilineage glioblastoma models. Advances in biological regulation. 2019:100658.

5.         Jacob F, Salinas RD, Zhang DY, Nguyen PT, Schnoll JG, Wong SZH, et al. A Patient-Derived Glioblastoma Organoid Model and Biobank Recapitulates Inter-and Intra-tumoral Heterogeneity. Cell. 2019.

About the Author:

Dr. Willerth holds a Canada Research Chair in Biomedical Engineering at the University of Victoria where she has dual appointments in the Department of Mechanical Engineering and the Division of Medical Sciences as a Full Professor. She runs an active research group that engineers tissues from stem cells and is currently starting a company to sell bioinks for engineering neural tissues. She serves as the Acting Director for the Centre for Biomedical Research at the University of Victoria and on the steering committee of the B.C. Regenerative Medicine Initiative. Her honors include being named the 2018 REACH award winner for Excellence in Undergraduate Research-inspired Teaching, a Woman of Innovation in 2017, one of the 2015 Young Innovators in Cellular and Biological Engineering and a “Star in Global Health” by Grand Challenges Canada in 2014.  She spent Fall of 2016 on sabbatical at the Wisconsin Institute for Discovery supported by the International Collaboration on Repair Discoveries International Travel Award where she wrote her book “Engineering neural tissue using stem cells” published by Academic Press. She completed her postdoctoral work at the University of California-Berkeley after receiving her Ph.D. in Biomedical Engineering from Washington University. Her undergraduate degrees were in Biology and Chemical Engineering from the Massachusetts Institute of Technology.

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The post 3D Bioprinting Glioblastoma Models for Drug Screening appeared first on 3DHeals.

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Neurological diseases and disorders affect a significant percentage of people and this number will continue to increase as the population ages. For many diseases, like Alzheimer’s and Parkinson’s, no true long-term cure exists as current treatments only mitigate the symptoms of these devastating diseases. One of the major obstacles to developing effective treatments is that our current tools for screening potential drugs lack the ability to accurately predict whether a new drug will be both effective as well as non-toxic. Currently, the tools used for predicting the effects of potential drug targets include animal models and cadaveric human tissues. Animal models can be inaccurate with regards to predicting the toxicity and efficacy of drugs while human tissue samples tend to be limited in availability. Our group takes a different strategy where we use 3D bioprinting to generate neural tissue from pluripotent stem cells. Pluripotent stem cells possess two unique and defining properties. The first property is pluripotency which means they can become any cell type found in the body. These cells can also replicate to generate more stem cells, which is their second defining property. One way to produce pluripotent stem cells requires the reprogramming of adult cells back into stem cell-like state. These cells are called induced pluripotent stem cells (iPSCs) and they can be derived from patients suffering from neurodegenerative disorders. These iPSC lines can then be differentiated into tissues similar to those found the nervous system while replicating the features of these diseases, such as Alzheimer’s disease [1].

This combination of 3D printing with patient-derived iPSCs has the potential to generate models of neurological diseases in a dish for more accurate screening of potential drug targets. In my research group, we use Aspect Biosystem’s novel RX1 printer to generate our neural tissues as it is both quick and reproducible while being gentle on stem cells during the printing process [2]. It also enables us to print complex structures by positioning both cells and drug releasing microspheres in the appropriate places within our tissues. Our group has published a set of two papers showing that we can print neural tissues derived from human iPSCs while maintaining high levels of cell viability [3, 4]. These tissues can be cultured for extended periods of time (> 40 days) and they express mature neuronal markers. Similar proof of concept work has been done by Dr. Michael McAlpine’s group at the University of Minnesota where they used bioprinting to generate complex co-culture structures from stem cells that resemble the tissue found in the spinal cord [5].

In addition to generating personalized neural tissues for drug screening applications, pluripotent stem cells can also be directed to form structures that mimic the blood-brain barrier, which protects the central nervous system by limiting what materials can be transported into these tissues. Often getting drugs across the blood-brain barrier serves as a limiting step for potential therapeutics for treating neurodegenerative diseases and disorders.  As such, it is imperative to be able to model this structure in a dish when testing potential treatments. The Lippman group at Vanderbilt University recently reviewed the current progress related to generating such in vitro models [6]. Also, the Wellington group at the University of British Columbia validated a complex tissue-engineered model of the blood-brain barrier that could potentially be translated for bioprinting to increase throughput for drug screening applications [7].  Overall, the field of 3D bioprinting in combination with iPSC technology offers huge potential for developing personalized medicine approaches to identifying promising drug targets for treating neurological diseases and disorders.

References:

1. Willerth, S.M. Bioprinting neural tissues using stem cells as a tool for screening drug targets for Alzheimer’s disease. Journal of 3D Printing in Medicine. 2018. 2(4). p. 163-165.

3. Abelseth, E., Abelseth, L., de la Vega, L., Beyer, S., Wadsworth, S., and Willerth, S.M. 3D printing of neural tissues derived from human induced pluripotent stem cells using a fibrin-based bioink. ACS Biomaterials Science and Engineering. 2019. (5) p. 234-243.

4. de la Vega, L., Rosas Gomez, D., Abelseth, E., Abelseth, L., Alisson da Silva, V. and Willerth, S.M. 3D bioprinting human induced pluripotent stem cell-derived neural tissues using a novel Lab-on-a-Printer technology. Applied Science. 2018. 8(2414).  p. 1-13.

5. Joung, D., Truong, V., Neitzke, C.C., Guo, S., Walsh, P.J., Monat, J.R., Meng. M.F.  Park, S.H., Dutton, J.R., Parr, A.M. and McAlpine, M.C. 3D Printed Stem‐Cell Derived Neural Progenitors Generate Spinal Cord Scaffolds. Advanced Functional Materials. 2018. 28 (1801850). p. 1-10.

6. Bosworth, A.M., Faley, S.L., Bellan, L.M., and Lippmann, E.S. Modeling Neurovascular Disorders and Therapeutic Outcomes with Human-Induced Pluripotent Stem Cells. Frontiers in Biotechnology and Bioengineering. 2018. 5(87). p. 1-11.

7. Robert, J., Button, E.B., Yuen, B., Gilmour, M., Kang, K., Bahrabadi, A., Stukas, S., Zhao, W., Kulic, I., and Wellington, C.L. Clearance of beta-amyloid is facilitated by apolipoprotein E and circulating high-density lipoproteins in bioengineered human vessels. eLife. 2017. 10 (6). pii: e29595

About the author:

Dr. Willerth holds a Canada Research Chair in Biomedical Engineering at the University of Victoria where she has dual appointments in the Department of Mechanical Engineering and the Division of Medical Sciences as an Associate Professor. She serves as the Acting Director for the Centre for Biomedical Research at the University of Victoria and on the steering committee of the B.C. Regenerative Medicine Initiative. She also served as the President of the Canadian Biomaterials Society from 2017-2018. Her honors include being named the 2018 REACH award winner for Excellence in Undergraduate Research-inspired Teaching, a Woman of Innovation in 2017, one of the 2015 Young Innovators in Cellular and Biological Engineering and a “Star in Global Health” by Grand Challenges Canada in 2014.  She spent Fall of 2016 on sabbatical at the Wisconsin Institute for Discovery supported by the International Collaboration on Repair Discoveries International Travel Award where she wrote her book “Engineering neural tissue using stem cells” published by Academic Press. She completed her postdoctoral work at the University of California-Berkeley after receiving her Ph.D. in Biomedical Engineering from Washington University. Her undergraduate degrees were in Biology and Chemical Engineering from the Massachusetts Institute of Technology.

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