Keilholz AN, Lopez S, Attari M, Nguyen NP, Henry J, Smith CL, Feldberg A, Osman KL, Golzy M, Bunyak F, Lever TE, Nichols NL (2026) Impact of tongue exercise on hypoglossal axis survival, structure, and output in a rodent model of hypoglossal motor neuron degeneration. J Neurophysiol doi: 10.1152/jn.00631.2024 PMID: 42012472
Objective: To investigate the effects of a high-repetition/low-resistance tongue exercise paradigm on XII axis survival, structure, and output in adult male Sprague Dawley rats.
Summary: Intralingual injections of CTB-SAP result in decreased XII motor neuron survival and degenerative changes in the XII nerve consistent with what is seen in many motor neuron diseases. While these deficits are not mitigated by tongue exercise, the authors observed increased microglial fractional area/density in the XII nucleus of CTB-SAP + exercise rats.
Usage: Rats received intralingual injection of either CTB-SAP (IT-14) or unconjugated CTB + SAP (PR-01).
Today we’re highlighting one of our saporin conjugates, Kisspeptin-SAP. This is a tool for eliminating cells that express the human and sheep G-protein coupled receptor, GPR54.
Kisspeptin is a ligand to GPR54 and functions in the hypothalamus, placenta, liver, pancreas, adipose tissue, bone, and limbic regions which shows the importance it can play in diagnosis and treatment of various disorders. It is one of the neuropeptides that governs the reproductive endocrine axis by regulating neuronal activity and secretion of hypothalamic gonadotropin releasing hormone (GnRH). GnRH is released from the hypothalamus to act on the anterior pituitary triggering the release of luteinizing hormone (LH), and follicle stimulating hormone (FSH). These gonadotropic hormones lead to sexual maturation and gametogenesis.
This is a 2023 publication using a Kisspeptin-saporin conjugate.
The objective of the authors was to test the functional role of ovine KNDy neurons in pulse generation and identify the roles of nearby Kiss1 receptor (Kiss1R)-containing cells. They performed these tests using conjugates NKB-SAP and Kisspeptin-SAP.
The results showed that NKB-SAP ablated over 90% of the KNDy cells, while Kisspeptin-SAP lesioned about two-thirds of the Kiss1R population. This led to a significant decrease in LH pulse amplitude and altering LH pulse patterns. NK3-SAP increased the interpulse interval without affecting the regularity of LH pulses, whereas Kiss-SAP disrupted their regular hourly occurrence but not the interpulse interval.
These findings suggest that KNDy neurons are critical for GnRH pulse generation in ewes, while ARC Kiss1R cells support the amplitude and regularity of these pulses, possibly as part of a positive feedback loop involving GABA or glutamate.
Babatunde OO, Bibby MG, Atala A, Almeida-Porada G, Porada CD (2026) In utero HSC transplantation for sickle cell disease: A potential therapeutic approach that overcomes complications of current therapies. Prenat Diagn doi: 10.1002/pd.70142 PMID: 41936060
Objective: To examine current evidence and recent advances for treatment of sickle cell disease (SCD).
Summary: Biotinylated anti‐c‐kit/CD117 mAb coupled to a streptavidin‐conjugated saporin has been used to selectively deplete host HSC while preserving the host’s immune system. A single intravenous dose of the anti‐CD45‐saporin ADC enabled > 90% donor (congenic) hematopoietic engraftment and full correction of the SCD phenotype.
Serambeque B, Dias I, Mestre C, Marto CM, Botelho MF, Carvalho MJ, Laranjo M (2026) Photodynamic therapy-based strategies targeted at cancer stem cells: A scoping review. Cancers (Basel) 18(7):1162. doi: 10.3390/cancers18071162 PMID: 41976384
Objective: To examine strategies for targeting cancer stem cells using photodynamic therapy.
Summary: Photochemical internalization (PCI) is a widely adopted approach for targeting surface markers on cancer stem cells. Anti-CD133-SAP was evaluated in colorectal cancer, breast cancer, and melanoma. In CD133high colorectal cancer cells (WiDr), PCI with picomolar concentrations of AC133–saporin completely inhibited viability and colony formation, with no toxicity observed in the absence of light activation. Similar efficacy was observed in CD133+ breast (MDa-MB-231) and CD133high melanoma cells (FMEX-1) but not in CD133− breast cancer cells (MCF7), confirming target specificity. A similar strategy was employed to target CD44 in human cancer cell lines.
Cardani S, Janes TA, Asif R, Pagliardini S (2026) Sex differences in the effects of etonogestrel on respiratory recovery in an in vivo rat model of central chemoreflex impairment. Acta Physiol (Oxf) 242(4):e70194. doi: 10.1111/apha.70194 PMID: 41823358
Objective: Chronic etonogestrel (ETO) treatment improved the CO2 chemoreflex in female rats in which <80% of chemoreceptor neurons comprising the retrotrapezoid nucleus (RTN) were eliminated. Since the progesterone receptor is widely expressed in both the male and female brain, authors investigated the effects of ETO on respiratory recovery.
Summary: Authors used SSP-SAP to partially eliminate RTN neurons. Dose-dependent impairment of the CO2 chemoreflex in both sexes following chemoreceptor lesion corroborates the findings that ETO treatment restores ventilation in female rats with moderate-sized lesions.
Usage: Four microinjections (150 nL per injection) were made with Substance P-conjugated saporin toxin (SSP-SAP, IT-11) and fluorescent carboxylate-modified Fluospheres TM to label injection sites.
Today we’re highlighting one of our saporin conjugates, Anti-CD117-SAP. This is a tool for depleting cells that express CD117, the tyrosine kinase growth factor receptor.
CD117 is expressed on hematopoietic stem cells, mast cells, and acute myeloid leukemia cells. Some of the areas where CD117 plays an essential role is in the regulation of cell survival and proliferation, hematopoiesis, stem cell maintenance and mast cell development, migration and function.
Allogeneic hematopoietic stem cell transplantation can cure genetic diseases such as severe combined immunodeficiency (SCID), but it’s associated with significant toxicities such as graft-versus-host disease (GvHD). Using a patients’ own gene-modified hematopoietic stem and progenitor cells (HSPCs) can eliminate the risk of GvHD, but the treatment relies on gene transfer using viruses and genotoxic conditioning which carries risks.
The authors describe how base-editing is an alternative means to correct genetic defects while engineered virus-like particles (eVLPs) can deliver the base-edited proteins without the risks seen with viral integration.
In conclusion, transplantation of HSPCs that have been repaired through eVLP-mediated base-editing with CD117-ADC conditioning successfully reversed the SCID phenotype in mice, and highlights a significant advancement in disease treatment without the current toxicities.
We are highlighting one of our saporin conjugates, Neurotensin-SAP — a tool for depleting cells that express the neurotensin receptor (NTSR).
Neurotensin is a 13-amino-acid peptide found in the brain and spinal cord and is released by the hypothalamus. It is synthesized as part of a larger precursor protein that also includes the related neuropeptide neuromedin N. Neurotensin affects pituitary hormone release, interacts with the dopaminergic system, and is involved in vasodilation and hypotension. It can also modulate pain perception where intrathecal neurotensin has also been shown to be anti-nociceptive.
The objective was to determine whether NTSR1-expressing enteropancreatic neurons mediate the glucose-lowering effects of dietary olive oil and neurotensin, and to characterize their physiological role in glucose homeostasis.
The authors unilaterally injected neurotensin-SAP into the nodose ganglia to ablate NTSR1-expressing vagal neurons.
In their study, they demonstrated that neurotensin improves glucose tolerance by activating NTSR1-expressing enteropancreatic neurons, which connect the gut and pancreas. Ablation or disruption of these neurons abolished the glucoregulatory effects of both neurotensin and olive oil, establishing their necessity and sufficiency in this pathway.
Wang W, Zhang Y, Li L, Xu Y, Zhang W, Chen X, Wang X, Tong G, Zhang P (2026) PACAP/PAC 1 modulates light-induced sleep via the ipRGC-VLPO pathway. Biochem Biophys Res Commun 808:153462. doi: 10.1016/j.bbrc.2026.153462 PMID: 41702189
Objective: To investigate the mechanism of PACAP in ipRGC–VLPO light-induced sleep.
Summary: Partial ablation of ipRGCs by Melanopsin-SAP reduced light-induced sleep duration, whereas PACAP 1-38 administration reversed this effect, leading to an increase in REM sleep. After the partial destruction of ipRGCs through the intraocular injection of saporin (SAP), we continued to observe the effect of PACAP on light-induced sleep. The results showed that after the microdialysis injection of PACAP 1-38 into the VLPO of SAP mice, the light-induced sleep of the mice increased; specifically, REM sleep significantly increased. The results suggest that PACAP is involved in ipRGC–VLPO-mediated light-induced sleep.
Today’s topic is time-course for our saporin conjugates. Common questions we get are (1) how long does it takes to see cell death, (2) how long should I wait before performing histology on an animal, or (3) how long before I see behavioral changes in an animal?
In this image from Mantyh et. al. (1997), we are looking at confocal imagery of the binding and internalization of our peptide conjugate SP-SAP to the NK1r receptor in primary cultures of neonatal spinal cord neurons.
As you can see, conjugate binding occurs immediately where within hours, the SP-SAP has recognized and bound to the NK1 receptor. Here we see the areas of concentrated NK1R expression marked by yellow immunofluorescence.
But how long until you see cell death? Here is a cytotoxicity graph of in vitro data of our antibody conjugate 192-IgG-SAP. These are typical data after cells have been treated for 3 days, which is standard protocol.
Waite et al. (1994) used 192-IgG-SAP and showed the appearance of behavioral effects associated with neuronal loss at day four and plateauing at day 7.
This coincides with the time course seen in vitro. At this point, microglia will infiltrate, but stop at 7 days, which is probably the peak day for infiltration. Once there is complete removal of the detritus, microglia down-regulate and at 14 days all debris is cleared and the animal begins to regain normal eating and sleeping habits. This is the idea behind waiting about 2 weeks before performing histology.
Spedding M (2025) Does amyotrophic lateral sclerosis (als) have metabolic causes from human evolution?. Cells 14(21):1734. doi: 10.3390/cells14211734 PMID: 41227379
Objective: To evaluate if recent human genetic variants play major roles in Amyotrophic Lateral Sclerosis (ALS), changing metabolism.
Summary: The authors reviewed Cholera Toxin B (CTB) binding as a tool to study GM1 and fucosylated structures, and to cause denervation. Findings suggest CTB may be used as a surrogate marker of GM1. CTB-SAP causes specific motor neuron death, presumably by binding to and downregulating GM1, and possibly other fucosylated targets; powerful evidence linking loss of GM1 to denervation in ALS.
