Propranolol for Surgeons in the Treatment of Infantile Hemangiomas

Mechanism and application of β-adrenoceptor blockers in soft tissue wound healing

Soft tissue damage stimulates sympathetic nerves to release large amounts of catecholamine hormones which bind to β-adrenergic receptors (β-ARs) on the cell membrane surface. It activates the downstream effector molecules and impairs soft tissue wound healing. β-blockers specifically inhibit β-ARs activation in acute/chronic skin lesions and ulcerative hemangiomas. They also accelerate soft tissue wound healing by shortening the duration of inflammation, speeding keratinocyte migration and reepithelialization, promoting wound contraction and angiogenesis, and inhibiting bacterial virulence effects. In addition, β-blockers shorten wound healing periods in patients with severe thermal damage by reducing the hypermetabolic response. While β-blockers promote/inhibit corneal epithelial cell regeneration and restores limbal stem/progenitor cells function, it could well accelerate/delay corneal wound healing. Given these meaningful effects, a growing number of studies are focused on examining the efficacy and safety of β-blockers in soft tissue wound repair, including acute and chronic wounds, severe thermal damage, ulcerated infantile hemangioma, corneal wounds, and other soft tissue disorders. However, an intensive investigation on their acting mechanisms is imperatively needed. The purpose of this article is to summerize the roles of β-blockers in soft tissue wound healing and explore their clinical applications.

Alpha and beta adrenergic receptors modulate keratinocyte migration

Keratinocyte migration into skin wounds is the step of the healing process that correlates with the wound closure rate. Keratinocyte migration, and wound epithelialization are decreased when beta 2-adrenergic receptors (B2AR) are activated by 1 μM epinephrine/adrenaline, resulting in delayed wound healing in human and mouse skin. In the present study, we found paradoxically, that in a subset of keratinocyte strains exposure to low concentrations of epinephrine (0.1 nM) increased, rather than decreased, their migratory rate. We find that both the alpha- and the beta-adrenergic receptors are expressed in human keratinocytes, and expression of alpha-2 AR subtypes demonstrated for the first time. Therefore, we tested if the alpha-AR could be modulating the increased migratory response observed in these cell strains. By using specific inhibitors to alpha-AR, we demonstrated that blocking A2B-AR could reverse the rapid cell migration induced by the 0.1 nM epinephrine. Phosphorylation of ERK was elevated after 1-10 minutes of the low epinephrine treatment and the A2B-AR inhibitor blocked the ERK phosphorylation. The results suggest that both the A2B-AR and B2AR mediate keratinocyte migration, in which with a low level of epinephrine treatment, A2B-AR could alter the B2AR signals and regulate the migration rate.

Propranolol vs. steroids in the treatment of infantile hemangiomas: A meta-analysis

Infantile hemangioma (IH) is a common disease, and drug therapy is the most common treatment method. Clinically, steroids have long been used as first-line drugs, but in recent years, some doctors have begun to use propranolol to treat infantile hemangiomas (IHs). The present study performed a meta-analysis to evaluate the clinical effects of propranolol in comparison with steroids in the treatment of infantile hemangiomas. A detailed review of the literature on PubMed, Cochrane Library, Embase and Web of Science was performed prior to March 31, 2020. All literatures were compared with the clinical effects of propranolol and steroids in the treatment of infantile hemangiomas. A total of two researchers independently screened the literature according to the selection criteria, extracted data and assessed the risk of bias for the included studies. Review Manager 5.3 was used to meta-analyze all the included studies. According to the selection criteria, nine articles were included in the present study. The meta-analysis revealed that the effective rate of propranolol was greater than that of steroids in treating infantile hemangiomas [odds ratio (OR), 3.96, 95% confidence interval (CI), 2.47-6.37; P<0.00001]. Additionally, propranolol had fewer complications than steroids (OR, 0.21; 95% CI, 0.12-0.36; P<0.00001). The recurrence rate of the two groups was not statistically different (OR, 1.83; 95% CI, 0.59-5.70; P=0.3) and the surgical resection rate of propranolol was lower than steroids (OR, 0.19; 95% CI, 0.08-0.46; P=0.0002). The present study demonstrated that propranolol is more effective than steroids for the treatment of IHs, and provides a theoretical basis for the clinical use of propranolol as an alternative to steroids.