Comments on the Retraction by PLoS ONE of a Laboratory Study on Arnica montana
25 June 2019
27 June 2019
05 August 2019 (eFirst)
In June 2019, the journal PLoS ONE retracted an original research article, published in 2016, which described the effects of homeopathic Arnica montana on interleukin-4 treated human macrophages. The results showed an increase in extracellular matrix gene expression, including the gene encoding fibronectin, which is one of the main proteins involved in connective tissue healing. Here, the authors of the article discuss the critical points raised by the journal in the retraction note, with a focus on the specific methodological aspects of research on high dilutions of natural compounds. The editorial arguments made to justify the retraction did not prove any methodological errors, nor scientific misconduct. As a general rule, when a study published by a group of researchers raises scientific doubts because the results appear at variation with the commonly accepted knowledge in a field, the study is repeated by other scholars and any contrasting results are published and/or discussed. Therefore, retraction of the Arnica m. study by PLoS ONE is a violation of the conventions of scientific publication and knowledge-sharing methods derived from honest experimental method.
KeywordsArnica montana - gene expression - paper retraction - homeopathic dilutions - scientific literature
• Recently, the journal PLoS ONE has retracted an article showing the effects of Arnica montana on human macrophages.
• The arguments made to justify the retraction did not prove any methodological errors, nor misconduct.
• The reported effects on gene expression were admittedly low but statistically significant.
• Retracting the Arnica m. study appears as a violation of the conventions of the experimental method.
- 1 Marzotto M, Bonafini C, Olioso D. , et al. Arnica montana stimulates extracellular matrix gene expression in a macrophage cell line differentiated to wound-healing phenotype. PLoS One 2016; 11: e0166340
- 2 PLoS ONE Editors. Retraction: Arnica montana stimulates extracellular matrix gene expression in a macrophage cell line differentiated to wound-healing phenotype. PLoS One 2019; 14: e0219007
- 3 Alonso D, Lazarus MC, Baumann L. Effects of topical arnica gel on post-laser treatment bruises. Dermatol Surg 2002; 28: 686-688
- 4 Lawrence WT. ; Plastic Surgery Educational Foundation DATA Committee. Arnica. Plast Reconstr Surg 2003; 112: 1164-1166
- 5 Brinkhaus B, Wilkens JM, Lüdtke R, Hunger J, Witt CM, Willich SN. Homeopathic arnica therapy in patients receiving knee surgery: results of three randomised double-blind trials. Complement Ther Med 2006; 14: 237-246
- 6 Widrig R, Suter A, Saller R, Melzer J. Choosing between NSAID and arnica for topical treatment of hand osteoarthritis in a randomised, double-blind study. Rheumatol Int 2007; 27: 585-591
- 7 Iannitti T, Morales-Medina JC, Bellavite P, Rottigni V, Palmieri B. Effectiveness and safety of Arnica montana in post-surgical setting, pain and inflammation. Am J Ther 2016; 23: e184-e197
- 8 Bellavite P, Marzotto M, Bonafini C. Arnica montana experimental studies: confounders and biases?. J Integr Med 2018; 16: 72-76
- 9 Ho D, Jagdeo J, Waldorf HA. Is there a role for Arnica and Bromelain in prevention of post-procedure ecchymosis or edema? A systematic review of the literature. Dermatol Surg 2016; 42: 445-463
- 10 Kriplani P, Guarve K, Baghael US. Arnica montana L.—a plant of healing: review. J Pharm Pharmacol 2017; 69: 925-945
- 11 Lee HS, Yoon HY, Kim IH, Hwang SH. The effectiveness of postoperative intervention in patients after rhinoplasty: a meta-analysis. Eur Arch Otorhinolaryngol 2017; 274: 2685-2694
- 12 Marzotto M, Bonafini C, Olioso D, Bellavite P. Study of the action mechanisms of Arnica montana effects on macrophages. Int J High Dilution Res 2016; 15: 32-35
- 13 Elia V, Ausanio G, Gentile F, Germano R, Napoli E, Niccoli M. Experimental evidence of stable water nanostructures in extremely dilute solutions, at standard pressure and temperature. Homeopathy 2014; 103: 44-50
- 14 Klein SD, Wolf U. Comparison of homeopathic globules prepared from high and ultra-high dilutions of various starting materials by ultraviolet light spectroscopy. Complement Ther Med 2016; 24: 111-117
- 15 Betti L, Trebbi G, Kokornaczyk MO. , et al. Number of succussion strokes affects effectiveness of ultra-high-diluted arsenic on in vitro wheat germination and polycrystalline structures obtained by droplet evaporation method. Homeopathy 2017; 106: 47-54
- 16 Demangeat JL. Gas nanobubbles and aqueous nanostructures: the crucial role of dynamization. Homeopathy 2015; 104: 101-115
- 17 Demangeat JL. Nanosized solvent superstructures in ultramolecular aqueous dilutions: twenty years' research using water proton NMR relaxation. Homeopathy 2013; 102: 87-105
- 18 Elia V, Germano R, Napoli E. Permanent dissipative structures in water: the matrix of life? Experimental evidences and their quantum origin. Curr Top Med Chem 2015; 15: 559-571
- 19 Guedes JRP, Bonamin LV, Capelozzi VL. Water-related mechanisms proposed for storing and transmitting homeopathic information: putative links with biological responses. Homeopathy 2018; 107: 172-180
- 20 Van Wassenhoven M, Goyens M, Capieaux E, Devos P, Dorfman P. Nanoparticle characterisation of traditional homeopathically manufactured Cuprum metallicum and Gelsemium sempervirens medicines and controls. Homeopathy 2018; 107: 244-263
- 21 Bellavite P, Signorini A, Marzotto M, Moratti E, Bonafini C, Olioso D. Cell sensitivity, non-linearity and inverse effects. Homeopathy 2015; 104: 139-160
- 22 Holandino C, Oliveira AP, Homsani F. , et al. Structural and thermal analyses of zinc and lactose in homeopathic triturated systems. Homeopathy 2017; 106: 160-170