Because these experiments used different injury models, the researchers assessed different aspects of the resulting nerve-related changes. The studies therefore provide separate sets of experimental measurements rather than a common dataset for direct comparison. This article examines the reported measurements from each research model separately and keeps the findings of the two peptides distinct.
What Do Researchers Measure in Experimental Nerve Injury Models?
The studies reported these measurement categories:
- Functional measurements
- Electrophysiological measurements
- Structural measurements
- Cellular measurements
- Molecular measurements
What Has BPC-157 Research Measured in Nerve Injury Models?
Functional and Electrophysiological Measurements
The BPC-157 study examined transected rat sciatic nerves using electromyography (EMG), motor action potentials and the sciatic functional index (SFI). EMG was assessed one and two months after injury. Walking recovery was assessed using SFI at weekly intervals.
The study reported increased motor action potentials and improved SFI in the BPC-157-treated rats.
Structural and Morphometric Measurements
The study examined neural fascicle presentation, regenerative fiber density, and regenerative fiber size. It reported improved neural fascicle presentation, a homogeneous regeneration pattern, and increased density and size of regenerative fibers.
The researchers also measured myelinated-fiber diameter, myelin-sheet thickness, and the number of myelinated fibers per area. The study reported increased diameter, increased myelin-sheet thickness, and increased numbers of myelinated fibers per area.
Additional measurements included myelinated fibers as a percentage of the transected nerve area, nerve tissue composition, and blood-vessel presentation. The study reported a higher proportion of neural tissue relative to connective tissue and increased blood-vessel presentation.
What Has ARA-290 Research Measured in Nerve Injury Models?
Sensory and Behavioral Measurements
In the spared-nerve-injury model, researchers measured mechanical allodynia and cold allodynia. ARA-290 produced a dose-response effect on mechanical allodynia with significant reductions reported up to 20 weeks compared with vehicle treatment. Reductions in cold allodynia were also reported up to 20 weeks.
In the neuritis model, researchers measured mechanical allodynia and heat hyperalgesia. Vehicle-treated animals developed both responses. The study reported differences in mechanical allodynia between the ARA-290 and vehicle groups while no significant difference was reported for heat hyperalgesia.
Neural and Inflammatory Measurements
The spared-nerve-injury study measured Iba-1 immunoreactivity and GFAP immunoreactivity. Iba-1 immunoreactivity was used to examine the spinal microglia response, while GFAP immunoreactivity was used to examine the astrocyte reaction.
At two weeks after the lesion, significant microglia reactivity was observed in the vehicle-treated animals compared with sham-operated animals. The animals treated with the tested ARA-290 treatments did not show an increase at that observation point. At 20 weeks, increased microglia reactivity was observed in the vehicle and lower-treatment groups, while the higher tested treatment group did not show increased microglia reactivity.
The same study reported no difference in astrocyte reaction based on GFAP immunoreactivity.
The neuritis study measured TNF-α mRNA and CCL2 mRNA in the nerve and Gelfoam using polymerase chain reaction. The study reported no significant difference in TNF-α or CCL2 mRNA levels following ARA-290 treatment compared with vehicle-treated animals.
How Do the BPC-157 and ARA-290 Research Models Differ?
The BPC-157 study used a traumatic sciatic-nerve transection model and reported functional, electrophysiological, structural, and morphometric measurements.
The ARA-290 studies used spared-nerve-injury and neuritis models. Their reported measurements included sensory behavioral responses, spinal microglia and astrocyte responses, and selected molecular markers.
The models and measured endpoints were different, so the reported findings do not constitute a direct head-to-head comparison of BPC-157 and ARA-290.
What Are the Main Limitations of These Nerve Injury Studies?
The BPC-157 study used sciatic-nerve transection, whereas the ARA-290 studies used spared-nerve injury and neuritis models.
The studies also used different measurements. BPC-157 research included SFI, EMG, motor action potentials, and nerve morphometry. ARA-290 research included mechanical allodynia, cold allodynia, heat hyperalgesia, Iba-1 immunoreactivity, GFAP immunoreactivity, TNF-α mRNA, and CCL2 mRNA.
The reviewed experiments therefore do not provide measurements from the same injury model using the same endpoint set for both peptides. Their findings should not be treated as equivalent measurements.
The studies reviewed here are experimental studies in animal models. The reported findings do not establish efficacy in humans.
FAQs
References
- Gjurasin M, Miklic P, Zupancic B, Perovic D, Zarkovic K, Brcic L, Kolenc D, Radic B, Seiwerth S, Sikiric P. Peptide therapy with pentadecapeptide BPC 157 in traumatic nerve injury. Regul Pept. 2010 Feb 25;160(1-3):33-41. PubMed ↗
- Swartjes M, van Velzen M, Niesters M, Aarts L, Brines M, Dunne A, Cerami A, Dahan A. ARA 290, a peptide derived from the tertiary structure of erythropoietin, produces long-term relief of neuropathic pain coupled with suppression of the spinal microglia response. Mol Pain. 2014 Feb 16;10:13. PubMed ↗
- Pulman KG, Smith M, Mengozzi M, Ghezzi P, Dilley A. The erythropoietin-derived peptide ARA290 reverses mechanical allodynia in the neuritis model. Neuroscience. 2013 Mar 13;233:174-83. PubMed ↗