Project Summary/Abstract
Chronic low back pain is a debilitating disorder of significant socio-economic importance and a major gateway
to opioid use. Therefore, minimally invasive non-addictive treatments that aim to address pain by targeting the
underlying disease pathology are critical to improve human health and limit the growing opioid crisis.
Intervertebral disc (IVD) degeneration is strongly associated with the pathophysiology of chronic low back pain;
specifically extracellular matrix (ECM) breakdown, inflammation, and aberrant nerve/vascular ingrowth, all of
which are significantly correlated with “Discogenic back pain” (DBP). Therefore, the overall objective of this
proposal is to develop novel non-viral reprogramming-based therapies to convert degenerate nucleus
pulposus (NP) and annulus fibrosus (AF) IVD cells associated with DBP, into a healthy pro-anabolic,
anti-nerve/vascular phenotype, using engineered extracellular vesicles (eEVs). Our central hypothesis is
that non-viral reprogramming will restore IVD structure/mechanical function, and limit nerve/vascular ingrowth
associated with pain, by converting the patient’s own degenerate IVD cells into a pro-anabolic phenotype in situ.
To date, clinicians do not have access to the necessary biological tools to treat IVD degeneration in patients
with DBP. A critical barrier to the success of current biologic strategies involves significant logistical and
regulatory challenges such as a lack of sustained drug delivery systems, poor long-term cell viability or viral
reprogramming that permanently integrates with the host DNA. Our non-addictive strategy focuses on
addressing these limitations. Through our recent R61 award and published work, we have shown that human
NP cells can be reprogrammed towards a healthier phenotype using developmental transcription factors
Brachyury or FOXF1, showing increased ECM accumulation and decreased catabolic/ inflammatory/
neurotrophic factors - all key features of a healthy IVD. Furthermore, in our mouse DBP in vivo model we have
also demonstrated significant improvement in NP tissue hydration and dampened pain behaviors in animals
treated with eEVs loaded with FOXF1 for up-to 12 weeks, highlighting the potential of our proposed strategy to
restore structure/function of the IVD while reducing pain. However, critical gaps remain such as i) understanding
the synergistic reprogramming potential of multiple developmental transcription factors in NP and AF cells, ii)
how sex and age influence our strategy, and iii) evaluating therapeutic efficiency using more clinically relevant
in vivo animal models that simulate the human condition and functionalized eEVs to deliver transcription factors
to specific cell types within the IVD (for example, NP or AF cells).
Our first aim investigates the synergistic effects of eEVs loaded with multiple transcription factors using in
vitro and in vivo clinically relevant models of DBP, and quantifying efficacy of our strategy via assessment of IVD
structure/function and pain markers. The second aim involves functionalizing the eEVs with ligands specific for
NP or AF cells to selectively deliver cargo to degenerate NP or AF cells of the IVD in vitro and in vivo.
