Periodic Reporting for period 4 - HUMAN TEXTILES (Human, Woven, Tissue-Engineered Blood Vessels (TEBV) Exclusively from Cell-Assembled Extracellular Matrix (CAM).)
Periodo di rendicontazione: 2023-05-01 al 2024-10-31
Currently, when small diameter blood vessels are obstructed, we sometimes have to replace them. The best option is to use a “less important” vessel and transplant it within the same patient. This is done, for example, when a vein from the leg is used to replace one on the heart. We also sacrifice healthy vessels to connect people with failed kidneys to a hemodialysis machine. Of course, we do not have a large supply of vessels that can be spared, and, unfortunately, these transplanted vessels most often do not last for the rest of the life of the patient. When biological vessels are not (no longer) available, surgeons use special plastic tubing. Unfortunately, the body recognizes these so-called “biomaterials” as foreign and will try to degrade them. This will cause inflammation, fibrosis, and thrombosis that can all lead to failure of the conduit. In addition, these materials can hide microorganism from the immune system and cause deadly infection. Also, these materials are very stiff compared to biological tissues and this will add to the poor ability of these synthetic grafts to work as blood vessels, especially when diameters are smaller than 5-6 mm.
With our current eating habits and more sedentary lifestyle, disease of the blood vessels (cardiovascular) is the most important cause morbidity and mortality in the richer countries. The need for hemodialysis, which linked to diabetes and hypertension, is also very important (about 2 million worldwide) and will likely increase at the population ages. Clearly, finding better blood vessel replacements would improve the life of millions.
Our approach is to produce biological vessels in the lab by using human cells in culture. This would avoid the use of synthetic materials that the body recognized as foreign while insuring an infinite supply of replacement vessels. We have previously shown that cells can lay down a sheet of material (called extracellular matrix) in the right culture conditions. We have previously shown that this cell-assembled matrix (CAM) can be used to produce vessel by rolling the sheets and that these vessels can perform well in humans. In this project, we want to create blood vessels by weaving yarn made from CAM because this will allow the production of vessels much more rapidly (so less expensively), reliably, and with better control over their properties. Our objectives are to 1) Create and characterize CAM yarn made in the lab with human and a large animal cells, 2) Test the biocompatibility (under the skin) of theses yarns in vivo (test human in an immunosuppressed rat model and the large animal yarn in the same selected large animal species), 3) Weave small diameter vessels with human and animal yarn, characterize them in vitro, and optimize their properties, and 4) Implant large animal woven vessels in the arterial circulation of the same species and evaluate their performance.
With our current eating habits and more sedentary lifestyle, disease of the blood vessels (cardiovascular) is the most important cause morbidity and mortality in the richer countries. The need for hemodialysis, which linked to diabetes and hypertension, is also very important (about 2 million worldwide) and will likely increase at the population ages. Clearly, finding better blood vessel replacements would improve the life of millions.
Our approach is to produce biological vessels in the lab by using human cells in culture. This would avoid the use of synthetic materials that the body recognized as foreign while insuring an infinite supply of replacement vessels. We have previously shown that cells can lay down a sheet of material (called extracellular matrix) in the right culture conditions. We have previously shown that this cell-assembled matrix (CAM) can be used to produce vessel by rolling the sheets and that these vessels can perform well in humans. In this project, we want to create blood vessels by weaving yarn made from CAM because this will allow the production of vessels much more rapidly (so less expensively), reliably, and with better control over their properties. Our objectives are to 1) Create and characterize CAM yarn made in the lab with human and a large animal cells, 2) Test the biocompatibility (under the skin) of theses yarns in vivo (test human in an immunosuppressed rat model and the large animal yarn in the same selected large animal species), 3) Weave small diameter vessels with human and animal yarn, characterize them in vitro, and optimize their properties, and 4) Implant large animal woven vessels in the arterial circulation of the same species and evaluate their performance.
We have produced threats from human cells and have learned a lot about their mechanical properties and biological structure. We have carefully studied the composition of human CAM produced with cells from over 20 different donors and have shown that there is a large variability in the composition of the ECM which provides a reference for the entire field of Tissue Engineering that relies on ECM production. We have identified sheep (ovine) as the best large animal model to produce CAM in vitro. We have shown that human and sheep CAM have very similar mechanical properties but slightly different protein composition.
We have developed a model of subcutaneous implantation of human yarn in nude rats (immunosuppressed rats). We have shown that these rats will not reject human CAM but will degrade extracellular matrix that has been denatured. With this model, we have shown that the CAM yarn is well tolerated and is still present and largely untouched after 6 months. Similarly, ovine threads have been implanted in the subcutaneous space of sheep and also have been shown to be stable for six months. In contrast, we show that human threads of CAM, even decellularized, cause an intense immune reaction.
We have learned to make woven vessels with human yarn and with ovine yarn. Both vessel types have promising mechanical properties. We have demonstrated that we can control the mechanical properties of the woven grafts by changing the weaving parameters. An optimized arteriovenous shunt was designed for implantation as an allogeneic implant in sheep.
Finally, we reached our ultimate goal to implant the optimized woven graft design into an arteriovenous shunt position in the sheep. These studies confirmed the feasibility of using these completely biological woven grafts in vivo and extremely stable mechanical behavior. Promising remodeling observations included rapid cellular migration from the anastomosis in the graft and low inflammatory response. However, calcification was also observed in high compression zones indicating that this phenomenon needs to be studied in futures projects. Puncturing the graph was also confirmed to be easy which is relevant for a hemodialysis application.
Overall, this project demonstrated the incredible potential of completely biological textiles made from CAM to be used to create implants with important mechanical roles that will be long lasting, non-inflammatory, and resistant to infections.
Results from the studies I have been published in peer reviewed scientific journals. Five articles have been published already and five more will be published shortly. This project has been widely covered by the general public media (BBC, CNN, New Scientist, WebMD, Medscape, New York Post, Daily Mail, etc. and French TV and magazines). This research has also provided preliminary data for two ”proof of concept” ERC grants that have provided preliminary data to secure a four-year national grant and a series of small grants to incubate a startup to develop a biological textile for urogenital repair
We have developed a model of subcutaneous implantation of human yarn in nude rats (immunosuppressed rats). We have shown that these rats will not reject human CAM but will degrade extracellular matrix that has been denatured. With this model, we have shown that the CAM yarn is well tolerated and is still present and largely untouched after 6 months. Similarly, ovine threads have been implanted in the subcutaneous space of sheep and also have been shown to be stable for six months. In contrast, we show that human threads of CAM, even decellularized, cause an intense immune reaction.
We have learned to make woven vessels with human yarn and with ovine yarn. Both vessel types have promising mechanical properties. We have demonstrated that we can control the mechanical properties of the woven grafts by changing the weaving parameters. An optimized arteriovenous shunt was designed for implantation as an allogeneic implant in sheep.
Finally, we reached our ultimate goal to implant the optimized woven graft design into an arteriovenous shunt position in the sheep. These studies confirmed the feasibility of using these completely biological woven grafts in vivo and extremely stable mechanical behavior. Promising remodeling observations included rapid cellular migration from the anastomosis in the graft and low inflammatory response. However, calcification was also observed in high compression zones indicating that this phenomenon needs to be studied in futures projects. Puncturing the graph was also confirmed to be easy which is relevant for a hemodialysis application.
Overall, this project demonstrated the incredible potential of completely biological textiles made from CAM to be used to create implants with important mechanical roles that will be long lasting, non-inflammatory, and resistant to infections.
Results from the studies I have been published in peer reviewed scientific journals. Five articles have been published already and five more will be published shortly. This project has been widely covered by the general public media (BBC, CNN, New Scientist, WebMD, Medscape, New York Post, Daily Mail, etc. and French TV and magazines). This research has also provided preliminary data for two ”proof of concept” ERC grants that have provided preliminary data to secure a four-year national grant and a series of small grants to incubate a startup to develop a biological textile for urogenital repair
This is the first demonstration of fully human and biological textile production. The development of human textiles made from CAM yarn is an important step forward in the development of fully biological tissue-engineered constructs. This is also the first demonstration of a large animal models CAM production that is similar to that of human CAM and creates a fantastic animal model to validate CAM-based products at a scale that is clinically relevant. The data coming out of the animal studies show important facts such as that: 1) nude rats can rapidly degrade ECM that was the denatured, while it accepts human CAM, 2) allogeneic CAM persists for at least six months (in the sheep model) showing a very slow remodeling as predicted, 3) xenogeneic CAM (human into sheep) triggers a strong immune response, demonstrating that xenogeneic ECM, even the decellularized, is recognized differently than allogenic ECM, contrary to what is often suggested in the literature. Overall, this project represent the leading edge of what has been done with CAM and biological textiles. It opens up many avenues to explore the use of CAM in an allogenic large-animal model.