Sympathetic nerve fibre in bone marrow — the wiring that sets the niche's daily rhythm, through beta-3 in health and beta-2 in leukaemia
also called SNS nerve fibre · adrenergic nerve fibre · marrow innervation · noradrenergic fibre
Bone marrow is wired: nerve fibres from the fight-or-flight system run alongside its small arteries and release noradrenaline on a daily schedule, which turns down the signal that holds blood stem cells in place and releases a pulse of them into the blood each day. Leukaemia damages these nerves, and so does chemotherapy.
The same thing, for a scientist
Sympathetic nerve fibres innervate bone marrow alongside arterioles and are a functional component of the HSC niche. Circulating HSCs and progenitors oscillate on a circadian rhythm in **antiphase with marrow Cxcl12**, and both the oscillation and the release are driven by core clock genes acting through circadian noradrenaline secretion from these local nerves, transmitted to stromal cells by the **beta-3 adrenergic receptor**, reducing nuclear Sp1 and rapidly downregulating Cxcl12 [E1]. Nestin+ MSCs are spatially associated with adrenergic fibres and their HSC-maintenance genes are selectively downregulated by beta-3 adrenoreceptor activation [E2]. In MLL-AF9 AML the wiring is destroyed and the receptor changes: leukaemia **disrupts SNS nerves**, abolishes Nestin+ niche-cell quiescence, and the leukaemogenesis-promoting adrenergic signal runs through the **beta-2, explicitly not the beta-3**, receptor on stromal cells [E3]. A 2025 letter generalises marrow neuropathy across drivers, documents severe ultrastructural fibre damage by electron microscopy in mouse models and human AML marrow, and notes that **chemotherapy itself induces niche neuropathy** [E4].
Marrow is innervated, and the innervation does something
That bones contain nerves is old anatomy; that those nerves regulate blood production is recent. The demonstration is 1: circulating HSC numbers rise and fall on a 24-hour cycle, peaking five hours after lights-on in a mouse and reaching a nadir five hours after dark, in antiphase with marrow Cxcl12. Disrupt the light cycle and the rhythm breaks. The transmission chain is clock genes to local noradrenaline release to the beta-3 receptor on stromal cells to reduced nuclear Sp1 to rapid Cxcl12 downregulation, and the physiological purpose the authors propose is that a daily release of stem cells during rest allows regeneration of the niche and of other tissues.
This matters practically for anyone who draws marrow or blood from a patient at a fixed clinic hour: the number of circulating stem and progenitor cells is a function of the time of day.
Two receptors, two directions
The single most useful fact in this entry is that the normal and the leukaemic adrenergic circuits use different receptors.
- Normal physiology: beta-3. Circadian Cxcl12 downregulation and HSC egress run through ADRB3 on stromal cells 1; beta-3 adrenoreceptor activation selectively downregulates HSC-maintenance genes in Nestin+ MSCs 2.
- MLL-AF9 leukaemia: beta-2. The adrenergic signalling that promotes leukaemogenesis is transduced by ADRB2 and explicitly not ADRB3 on stromal cells of leukaemic marrow 3.
An intervention designed from the circadian physiology — a beta-3 agonist such as mirabegron, which has been used to restore Nestin+ cells and reduce reticulin fibrosis in myeloproliferative neoplasm patients per the context cited in 4 — is therefore aimed at a different receptor from the one that carries the leukaemogenic signal. Conversely, beta-2 blockade is achievable with drugs as old and cheap as propranolol, which is licensed in infants for haemangioma, and has never been tested against KMT2A-rearranged leukaemia. That is recorded as an experiment (exp-beta2-blockade-kmt2a-xenograft) rather than as a recommendation.
The nerves are destroyed by the disease and by the treatment
MLL-AF9 AML disrupts marrow sympathetic fibres as it develops 3. A 2025 letter shows the same lesion in JAK2V617F MPN, NRAS-G12D pre-leukaemic myelopoiesis and p53-deletion lymphoid disease, and in human MPN and AML marrow, with severe ultrastructural damage visible by electron microscopy; chemically reinforcing the neuropathy promoted myeloid bias, reduced HSPC and MSC numbers and produced morphologically abnormal marrow vessels 4.
The letter's closing observation is the one with clinical weight: chemotherapy induces neuropathy of the HSC niche, and chemotherapy is first-line for every disease in which the neuropathy is pathogenic. If niche denervation favours the malignant clone, induction therapy plausibly deepens the lesion that favours the residual disease. That is the same structural claim already recorded for megakaryocytes, where chemotherapy inverts a quiescence signal into an expansion signal (cell-type-megakaryocyte), and it is the reason this beat treats treatment-induced niche remodelling as a distinct mechanism class rather than a footnote.
| ontology | CL:0000109 (peripheral neuron); fibres rather than somata are present in marrow |
|---|---|
| location | alongside arterioles; adjacent to Nestin+ MSCs |
markers
[ "tyrosine hydroxylase (TH)", "neurofilament", "noradrenaline release" ]
receptors on stroma
[
{
"receptor": "ADRB3 (beta-3)",
"role": "circadian Cxcl12 downregulation and HSC egress in health",
"source_evidence": "E1"
},
{
"receptor": "ADRB2 (beta-2)",
"role": "transduces the leukaemogenesis-promoting adrenergic signal in MLL-AF9 AML",
"source_evidence": "E3"
}
]circadian parameters
{
"peak_circulating_hspc": "5 h after light onset (mouse)",
"nadir": "5 h after darkness (mouse)",
"phase_relation": "antiphase with marrow Cxcl12"
}kmt2a relevance
{
"finding": "MLL-AF9 AML disrupts marrow sympathetic fibres; the pro-leukaemic adrenergic signal is beta-2",
"chemotherapy": "chemotherapy is reported to induce niche neuropathy, so the treatment may deepen the lesion the disease creates",
"literature_size": "the sympathetic/adrenergic x KMT2A PubMed intersection is 2 records, both cited here"
}untested pharmacology
[ "propranolol or other beta-2 blockade in KMT2A-rearranged models", "mirabegron (beta-3 agonist) as niche repair" ]
atlas refs
[
{
"label": "Circadian sympathetic control of Cxcl12 and HSC release",
"pmid": "18256599",
"title": "Haematopoietic stem cell release is regulated by circadian oscillations.",
"authors": "Méndez-Ferrer S, Lucas D, Battista M, et al.",
"venue": "Nature",
"year": 2008,
"title_provenance": "Title/authors/venue backfilled from PubMed esummary on 2026-09-20 because this citation stored a bare PMID with no title, which made it unscoreable by verify-citations.py. BACKFILLING IS NOT VERIFICATION: it confirms the PMID resolves to a real paper, not that this is the right paper for the claim. That still requires reading."
},
{
"label": "AML-induced sympathetic neuropathy and beta-2 signalling",
"pmid": "25017722",
"title": "Acute myelogenous leukemia-induced sympathetic neuropathy promotes malignancy in an altered hematopoietic stem cell niche.",
"authors": "Hanoun M, Zhang D, Mizoguchi T, et al.",
"venue": "Cell Stem Cell",
"year": 2014,
"title_provenance": "Title/authors/venue backfilled from PubMed esummary on 2026-09-20 because this citation stored a bare PMID with no title, which made it unscoreable by verify-citations.py. BACKFILLING IS NOT VERIFICATION: it confirms the PMID resolves to a real paper, not that this is the right paper for the claim. That still requires reading."
}
]- Beta-2 blockade in an infant risks bronchospasm in a population with frequent respiratory infection during neutropenia, and beta-blockade generally blunts the compensatory tachycardia that a septic or anaemic child depends on.
- Nerve fibres regenerate slowly and incompletely; a structural niche lesion may not be reversible on a timescale relevant to induction therapy.
- Manipulating the circadian axis to change HSC egress would also change the timing and the size of the leukaemic population in the circulation, which is the compartment MRD is measured in - a false signal risk as much as a therapeutic one.
- Does KMT2A::AFF1 infant B-ALL denervate the marrow as MLL-AF9 myeloid disease does? Nobody has looked, and the infant marrow's innervation has never been characterised.
- Is beta-2 blockade with propranolol - cheap, ancient, and licensed in infants for haemangioma - active against KMT2A-rearranged leukaemia in vivo, and is it additive with or antagonistic to a menin inhibitor?
- If chemotherapy denervates the niche, does the degree of denervation after induction predict relapse? Marrow nerve fibre density is measurable by immunohistochemistry on a trephine, so this is answerable in archived material.
- Does time of day affect measurable residual disease assays, given that circulating stem and progenitor numbers oscillate in antiphase with marrow CXCL12?
- E1strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Circulating HSCs and progenitors exhibit robust circadian fluctuations peaking 5 h after light onset and reaching a nadir 5 h after darkness, fluctuating in antiphase with bone-marrow Cxcl12 expression; the cyclical release and Cxcl12 expression are regulated by core clock genes through circadian noradrenaline secretion by sympathetic nerves delivered locally in the bone marrow and transmitted to stromal cells by the beta-3 adrenergic receptor, decreasing nuclear Sp1 and rapidly downregulating Cxcl12; the rhythm is markedly altered by continuous light or a 12 h phase shift.
Haematopoietic stem cell release is regulated by circadian oscillations · Mendez-Ferrer S, Lucas D, Battista M, Frenette PS · Nature 2008What this evidence cannot show
Mouse, nocturnal, so phase relative to human clock time is inverted. The receptor assignment relies on pharmacology with beta-3 agonists and antagonists whose selectivity is imperfect. The claim concerns egress of normal HSCs, not leukaemic cells. Read: abstract only.
Evidence that argues against this (1)
- The adrenergic receptor that matters changes in disease. In MLL-AF9 AML the leukaemogenesis-promoting adrenergic signal is transduced by beta-2 and explicitly not beta-3 on stromal cells, so the circadian beta-3 circuit is not the circuit a leukaemia-directed intervention would need to engage. Read: abstract only. Hanoun M et al. 2014
- E2strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Nestin-positive mesenchymal stem cells are spatially associated with adrenergic nerve fibres and highly express HSC-maintenance genes that are selectively downregulated during enforced HSC mobilization or on beta-3 adrenoreceptor activation.
Mesenchymal and haematopoietic stem cells form a unique bone marrow niche · Mendez-Ferrer S, Michurina TV, Ferraro F, Mazloom AR, Macarthur BD, Lira SA, et al. · Nature 2010What this evidence cannot show
Mouse, Nestin-GFP reporter; the nerve association is histological co-localisation. Whether the Nestin+ population is functionally distinct from LEPR+ perivascular cells is disputed. Read: abstract only.
Evidence that argues against this (1)
- Conditional deletion of Scf from Nestin-cre cells did not affect HSCs, so the nerve-associated Nestin+ cell is not the required source of the key maintenance factor, and the functional weight of the nerve-to-Nestin+-cell axis is correspondingly uncertain. Read: abstract only. Ding L et al. 2012
- E3strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper
Development of MLL-AF9 AML in mice disrupts sympathetic nervous system nerves and the quiescence of Nestin-positive niche cells, expanding osteoblast-primed mesenchymal stem and progenitor cells at the expense of HSC-maintaining NG2-positive periarteriolar niche cells, with the leukaemogenesis-promoting adrenergic signal transduced by the beta-2 but not the beta-3 adrenergic receptor expressed on stromal cells of leukaemic bone marrow.
Acute myelogenous leukemia-induced sympathetic neuropathy promotes malignancy in an altered hematopoietic stem cell niche · Hanoun M, Zhang D, Mizoguchi T, Pinho S, Pierce H, Kunisaki Y, et al. · Cell Stem Cell 2014What this evidence cannot show
Mouse myeloid model; no lymphoid, KMT2A::AFF1 or infant arm. Beta-2 versus beta-3 assignment rests on receptor-subtype pharmacology and genetics whose selectivity is not absolute. Read: abstract only.
Evidence that argues against this (1)
- Marrow sympathetic neuropathy is present in JAK2V617F MPN, NRAS-G12D pre-leukaemic myelopoiesis and p53-deletion lymphoid disease as well, and is also induced by chemotherapy, so the lesion is not specific to MLL-AF9 and may be a shared consequence of marrow disease rather than a mechanism this fusion drives. Read: abstract only. Bernal A et al. 2025
- E4moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
Neuropathy of the haematopoietic stem and progenitor cell niche emerges in NRAS-G12D-driven pre-leukaemic myelopoiesis and p53-deletion lymphoma/lymphoblastic leukaemia in addition to the previously reported JAK2V617F MPN and MLL-AF9 AML models, and is present in human MPN and AML marrow; it involves severe ultrastructural damage to sympathetic fibres on electron microscopy in NRAS-G12D mice and AML patients; chemically reinforced neuropathy promotes myeloid bias, reduces HSPC and mesenchymal stromal cell numbers and increases morphologically abnormal marrow blood vessels.
Bone marrow sympathetic neuropathy is a hallmark of hematopoietic malignancies and it involves severe ultrastructural damage · Bernal A, Cuminetti V, Serulla M, Florit A, Konieczny J, Golnarnik G, et al. · Experimental Hematology and Oncology 2025What this evidence cannot show
PubMed classifies the record as a Letter; methods are abbreviated. The statements that mirabegron restored nestin+ cells in MPN patients and that chemotherapy induces niche neuropathy are citations to prior work rather than results of this letter, and are recorded here as such rather than asserted. Neither new model is KMT2A-rearranged. Read: abstract only.
Evidence that argues against this (1)
- Generality cuts against mechanism-specificity: a lesion present in every driver tested and also produced by chemotherapy cannot by itself distinguish a mechanism the leukaemia exploits from a non-specific consequence of marrow disease. The MLL-AF9 study supplies the causal arm and the receptor assignment this generalisation lacks. Read: abstract only. Hanoun M et al. 2014
circadian noradrenaline sets marrow CXCL12 and HSC egress
- regulates →Nestin+ mesenchymal stem cell — the niche cell that MLL-AF9 leukaemia wakes up and then loses
adrenergic fibres abut Nestin+ MSCs; beta-3 activation downregulates their HSC-maintenance genes
MLL-AF9 AML disrupts marrow sympathetic fibres; chemotherapy reportedly does the same
readouts include marrow sympathetic fibre density by tyrosine hydroxylase immunohistochemistry