Israeli scientists unveil world’s first 3D-printed heart with human tissue

30 comments

  1. Cozy_Owee

    |Author

    Prediction,

    The cost to produce and replace a bad heart with it will be a few thousand dollars in most healthcare systems.

    Americans will need to mortgage their home, their parents home, then die of a heart attack post surgery after hearing insurance won’t cover it because it’s “not in their network”.

  2. Tfeth282

    |Author

    Hmm. This is interesting. It kind of sounds like they used hiPSCs to make that work, which is the obvious way we’d be doing this in the future, but at the moment it comes with some challanges. I work in a lab in a related field and I know that differentiating vascular tissue from stem cells is currently not a well developed art. Cells are missing characterisric aspects to their structure and end up in a mixed culture with other types of cell rather than being able to form one type of cell consistently when differentiated with current methods. Aspects of this are interesting, but other aspects of it are strange. Still, I’m only an undergrad working with a pretty narrow view of something slightly adjacent so take that as you will.

  3. katpillow

    |Author

    Sorry for the long response, but I spent a few years doing 3D printed organ scaffold research and want to help frame this if you’ll have me. First let it be clear, I am impressed by what they’ve done. I read the article, then looked at a few of the papers this lab has put out, in addition to the one correlated to this article. This is an exciting area of research, but the reality is that we are probably further from implementation than this article would suggest (as it always seems to be).

    I feel that it’s important to ground expectations when articles like this come out. The article makes mention toward the end of the challenges ahead for this, but there’s a significant lack of detail about how they actually printed these, as well as a few of the other challenges, but because it’s a journal article they don’t really detail the true scope of the problems at hand, so I will provide:

    1. 3D printed ECM hydrogels are INCREDIBLY weak from a structural/mechanical standpoint. The journal article mentions this, and claims that their cross-linking/curing process is able to overcome this limitation, but I have significant doubts. Hydrogels are great for creating (very) soft tissue environments, but for an organ which requires significant amount of structural strength and integrity, I am doubtful that the structure could survive the process of teaching the cells to contract, especially after removing the gelatin support medium. This is important, because cardiomyocyte maturity and functionality basically demands successful contraction and mechanical strain. This also requires sufficient cell density at the “teaching” stage, which brings me to my next point:

    2. I have big questions as to whether these cells could be printed/implanted into the scaffolding at a density that would be sufficient contractile function. Without high enough cell density, you won’t get enough cells gripping other cells, forming a unified contractile tissue. Not to mention that if it isn’t a uniformly grown tissue, that it would likely be leaky when pumping or lead to a blown wall later on. Yes, you can nurture the organ in vitro first, but it might take a really long time to get that organ into a functionally sustainable condition. If you’re someone that didn’t plan ahead (with a heart growing well in advance of the time you’d need it) then you might be out of luck, even if you start growing one right when you’re diagnosed with some form of heart disease or failure.

    Cardiac cell regeneration, even from stem cells like IPSCs, is one of the most difficult tasks currently on the plate for the regenerative medicine and biomaterials field. I acknowledge that there is some fairly conflicting info out there about this, but so far no one has actually been able to regenerate or generate large numbers of mature, normally functioning cardiomyocytes. For the sake of discussion and transparency in my points, some studies have stated that 30-50% of a heart’s cardiomyocytes can be grown/replaced in a year or less. However until someone does this with functional cells (and is able to control the process), I will defer to the perception that only about 1% of functional cardiomyocytes are turned over on a yearly basis.

    3. Adding to points made in the journal article: the complexity of a total organ, even one as simple as a heart (from a variety of cell-types perspective) is enormous. A lot more steps need to be taken to look at the nervous system components (arguably overcome to some degree via a pacemaker approach), the endothelial cells, the differences between cardiomyocytes at different levels in across the thickness of heart walls, and most importantly, the valves, which brings me to my final point…

    4. The valves. Arguably the most difficult component of a heart to engineer, especially from a biological perspective. The constant stress and strain that valves are subjected to is high, and the chordae tendineae (heart strings) that anchor the valves are normally about 80% collagen, which would differ significantly in composition, organization, and mechanical properties from the rest of the scaffold. Sure, you could use some of the artificial valves or pig valves currently used, but those come with their own complications that would probably beg the question “is it worth it?” when they likely limit the lifetime of a successfully printed and grown heart. In many cases, at that point you might as well just put the valves on the diseased heart (depending on the exact situation and need).

    5. Vascularization is always a huge challenge with these. In our lab, someone demonstrated that ECM-based hydrogels can be used to guide bile duct grown and organization, so I don’t see how it would be any different for veins and arteries. In our work, it was pretty dependent on using ECM derived from the liver though, so for blood vessels it may require using a similar approach of only cardiac or vessel ECM, which would be difficult to source enough of. Without the specific ECM, instead you might get non-preferential, higgildy-piggildy style vessel formation which doesn’t help anyone.

    I probably forgot something, as I wrote this up across a few different breaks, so feel free to add, counterpoint, etc etc etc

  4. tommygunz007

    |Author

    I remember a few years ago, I was over at r/3dprinting and someone asked me about printing tissue for science. I told them that actually printing biological tissue in K-Y Jelly is probably the best, because it’s primarily a sugar glycol base and that sugar could possibly be absorbed by the cells (I failed Biology in college I can’t recall) or washed off the cells, but it provides sufficient structure to print in.

    Fast forward to today when biological tissues can be printed in jelly.

    It’s an incredible world we live in.

  5. Tugsy

    |Author

    The potential for this is incredible. Assuming it got to a point where we could print organs/limbs ‘on demand’ it would save countless lives.

  6. Whynotfam

    |Author

    This article is terrible, it’s a blanket statement about the current limitations of tissue engineering and it does not go into any real information regarding the processes by which they achieved this feat

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