Beyond RNA Vaccines: The use of RNA to Engineer T-Cells to Treat Cardiac Fibrosis.

[NNadir]

The paper I'll reference in this post is this one: CAR T cells produced in vivo to treat cardiac injury Rurik et al., Science 375, 91–96 (2022)

The long effort over decades to develop RNA based treatments for disease finally came to fruition, as we all know, just in time to address the Covid crisis.

However, the technology was not originally proposed for vaccination, but to treat other diseases, including but not limited to, in most cases, genetic diseases, of which many are known.

A recent advance in medical science has been the exploration, and, in at least one case, development and commercialization of CAR-T cells, live immune cells designed to attack specific antigenic molecules (usually display proteins) associated with human disease.

(CAR = Chimeric antigen receptor)

CAR-T cells, as I understand it - I'm no expert in this technology - are generally produced in culture outside the body and then injected into it.

This paper refers to the engineering of CAR-T cells in the body, a very, very, very neat trick, although the generation of viral proteins without the virus, as is done in the RNA vaccines is also a very, very, very neat trick.

I won't discuss the full paper in any detail, but here's the opening text which describes a disease, cardiac fibrosis, and the engineering of CAR-T cells within the body, using RNA, to treat the disease:

Cardiac fibroblasts become activated in response to various myocardial injuries through well-studied mechanisms including transforming growth factor β–SMAD2/3, interleukin-11, and other interactions with the immune system (1–6). In many chronic heart diseases, these fibroblasts fail to quiesce and secrete excessive extracellular matrix, resulting in fibrosis (7). Fibrosis both stiffens the myocardium and negatively affects cardiomyocyte health and function (8). Despite in-depth understanding of activated cardiac fibroblasts, clinical trials of antifibrotic therapeutics have only demonstrated a modest effect (5, 7) at best. Furthermore, these interventions aim to limit fibrotic progression and are not designed to remodel fibrosis once it is established. To address this substantial clinical problem, we recently demonstrated the use of chimeric antigen receptor (CAR) T cells to specifically eliminate activated fibroblasts as a therapy for heart failure (9). Elimination of activated fibroblasts in a mouse model of heart disease resulted in a significant reduction of cardiac fibrosis and improved cardiac function (9). One caveat of that work is the indefinite persistence of engineered T cells similar to CAR T cell therapy currently used in the oncology clinical setting (10). Fibroblast activation is part of a normal wound-healing process in many tissues, and persistent antifibrotic CAR T cells could pose a risk in the setting of future injuries. Therefore, we leveraged the power of nucleoside-modified mRNA technology to develop a transient antifibrotic CAR T therapeutic.

Therapeutic mRNAs can be stabilized by the incorporation of modified nucleosides, synthetic capping, and the addition of lengthy poly-A tails, and can be enhanced with codon optimization (11–13). 1-Methylpseudouridine integration also boosts translation (13, 14). Direct introduction of mRNA into T cells ex vivo by electroporation has been used successfully by our group and others to make CAR T cells (15); however, this process carries significant cost and risk and requires extensive infrastructure. Thus, we developed an approach that could be used to avoid removing T cells from the patient by packaging modified mRNAs in lipid nanoparticles (LNPs) capable of producing CAR T cells in vivo after injection. LNP-mRNA technology underlies recent successes in COVID-19 vaccine development and holds exceptional promise for additional therapeutic strategies (16–20). Once in the body, mRNA-loaded LNPs, absent of any specific targeting strategies, are endocytosed by various cell types (especially hepatocytes if injected intravenously) (21, 22). Shortly after cellular uptake, the mRNA escapes the endosome, releasing the mRNA into the cytoplasm, where it is transiently transcribed before degrading (11). Targeting antibodies can be decorated on the surface of LNPs to direct uptake (and mRNA expression) to specific cell types (23, 24). We hypothesized that an LNP directed to T lymphocytes could deliver sufficient mRNAs to produce functional CAR T cells in vivo (Fig. 1A)...

Figure 1:



The caption:

FIG. 1. CD5-targeted LNPs produce functional, mRNA-based FAPCAR T cells in vitro.(A) Schematic outlining the molecular process to create transient FAPCAR T cells using CD5-targeted LNPs. (B and C) Representative flow cytometry analysis of GFP (B) and FAPCAR (C) expression in murine T cells 48 hours after incubation with IgG/LNP-FAPCAR, CD5/LNP-GFP, or CD5/LNP-FAPCAR. (D) Quantification of murine T cells (percentage) staining positive for FAPCAR from biologically independent replicates (n = 4). (E) FAPCAR T cells were mixed with FAP-expressing target HEK293T cells overnight and assayed for killing efficiency in biologically independent replicates (n = 3). Data are shown as mean ± SEM.

Very cool, very cool...

A general news item, a little less technical about the paper also appears in this Science issue:

T cells to fix a broken heart

It may be open sourced. The full technical paper requires a subscription to Science.

I trust your weekend has been pleasant and rewarding.

[WestMichRad]

1. Very cool!

Thanks for the synopsis.

Encapsulation of therapeutic molecules in lipid (or other) nanoparticles seems to me like a major new approach for medicines. I would think drug companies will also be looking at medicinal candidates that failed in past clinical trials to see if encapsulation might allow them to target specific tissues for receiving such treatments.

The skeptic in me wonders how much a drug company would try to charge for the therapy described in this paper. Would you pay a couple hundred thou to extend your life, say, 20 years?

[NNadir]

5. The technology is not entirely new. Liposomal doxorubicin is a rather old, but still widely used...

...drug. This drug involves the use of pegylation, and is formulated with certain phosphatyl choline based lipids.

I've been peripherally involved with developments in this technology for a long time.

This said, the new lipid formulations for RNA drugs is considerably more elegant and tightly controlled. The ionizable lipids have been designed with very specific attention to the membrane transport of RNA. A few months back a Chemical Reviews paper covered this topic: Lipids and Lipid Derivatives for RNA Delivery Yuebao Zhang, Changzhen Sun, Chang Wang, Katarina E. Jankovic, and Yizhou Dong Chemical Reviews 2021 121 (20), 12181-12277

I've downloaded the review but have not found time to read it.

As for cost, these single/low dose type compounds have challenging economics. In a world that would be more sensible than the one in which we live, we could weigh the costs of someone spending long periods in hospitalization in heart failure, against the cost of a very expensive but single dose drug and perhaps everybody would win.

We do not, however, live in a sensible world. The technology is very expensive to develop, given the necessary testing to evaluate safety, reliability and effectiveness. The scientists involved in the development, the cost of reagents, and indeed, economic reward for innovation all need to be addressed, but the question does not have an easy answer, I'm afraid.

Big blockbuster drugs most often do not cure diseases, but rather are utilized for chronic conditions. This is an unfortunate consequence of pharmaceutical economics. It's why we are likely to face a very serious antibiotic crisis at some point in the future.

Again, I don't have an answer, but the technology is indeed remarkable.

[YP_Yooper]

3. This is very cool

my close friend runs a team at U of Michigan looking to perfect mRNA for prostate/colorectal cancers for the past 10 years. The tech is very interesting

[NNadir]

6. My son has applied to U of Michigan for his Ph.D.

Some people think for his intended major it may be comparable or even better than MIT. (He's applying to nuclear engineering programs.) He applied to MIT as well. His mother and I hope for MIT since its closer to us, but I've been to Ann Arbor - albeit a long time ago - and I thought it a beautiful town.

The University of Michigan is an excellent institution.

I've been to a number of cities in Michigan. It's generally a very nice State from what I've seen of it.

[YP_Yooper]

7. See, I'm torn every which way

All family is from Michigan, I went to Ohio State for Chem Eng, but grew up in Pitt (and just moved back). Carnegie Mellon isn't so bad either, and closer to you than Ann Arbor

[NNadir]

8. Regrettably, Carnegie Mellon doesn't really have a nuclear engineering department.

My son's undergraduate degree and his Masters, which he's finishing up, are both in Materials Science Engineering, and I thought he should have looked at Carnegie Mellon, but for whatever reason, he didn't want to do so.

He wants his Ph.D. in nuclear engineering however and there are only a few schools offering first rate programs in that field. He's applied to what I think are the five best.

I'm very pleased with the education he got where he went. I have told him if he does well financially, he needs to seriously donate to that institution. He's a very good scientist. I thought he would have to work at an ice cream shop or equivalent for summer jobs, instead he's only worked under NSF grants or DOE programs, the latter at Oak Ridge. (I was a little jealous about the latter.) The close attention he got from the faculty made all that possible.

[YP_Yooper]

9. That's so fantastic!!

All the best

[niyad]

4. KNR and bookmarking for later. Fascinating.