Epithelial separation theory for post-tonsillectomy secondary hemorrhage: evidence in a mouse model and potential heparin-binding epidermal growth factor-like growth factor therapy. Eur Arch Otorhinolaryngol. 2018;275:569-578. [PMID: 29188436 DOI: 10.1007/s00405-017-4810-6]

Primary and secondary postoperative hemorrhage in pediatric tonsillectomy

BACKGROUND

Tonsillectomy is the most common procedure for treatment of pediatric recurrent acute tonsillitis and tonsillar enlargement that contributes to obstructive sleep apnea hypopnea syndrome. Postoperative hemorrhage of tonsillectomy is a life-threatening complication.

AIM

To identify the risk factors that may contribute to primary and secondary post-operative hemorrhage in pediatric tonsillectomy.

METHODS

The clinical data from 5015 children, 3443 males and 1572 females, aged 1.92-17.08 years, with recurrent tonsillitis and/or tonsil hypertrophy who underwent tonsillectomy in our hospital from January 2009 to December 2018 were retrospectively collected. The variables including sex, age, time of onset, diagnosis, method of tonsillectomy, experience of surgeon, time when the surgery started and monthly average air temperature were abstracted. The patients with postoperative hemorrhage were classified into two groups, the primary bleeding group and the secondary bleeding group, and their characteristics were compared with those of the nonbleeding group separately. Statistical analysis was performed by chi-square test with SPSS 20.

RESULTS

Ninety-two patients had post-tonsillectomy hemorrhage, and the incidence rate of post-tonsillectomy hemorrhage was 1.83%. The mean age was 5.75 years. Cases of primary hemorrhage accounted for approximately 33.70% (31/92), and cases of secondary hemorrhage occurred in 66.30% (61/92). The rate of reoperation for bleeding was 0.92%, and the rate of rehospitalization for bleeding was 0.88% in all patients. Multiple hemostasis surgery was performed in 6.52% (3/46) of patients. The method of tonsillectomy (coblation tonsillectomy) and experience of the surgeon (junior surgeon with less than 5 years of experience) were significantly associated with primary hemorrhage (χ² = 5.830, P = 0.016, χ²= 6.621, P = 0.010, respectively). Age (over 6 years old) and time of onset (more than a 1-year history) were significantly associated with secondary hemorrhage (χ²= 15.242, P = 0.000, χ²=4.293, P = 0.038, respectively). There was no significant difference in sex, diagnosis, time when the surgery started or monthly average air temperature. There was a significant difference in the intervention measures between the primary bleeding group and the secondary bleeding group (χ²= 10.947, P = 0.001). The lower pole and middle portion were the common bleeding sites, followed by the upper pole and palatoglossal arch.

CONCLUSION

The incidence rate of post-tonsillectomy hemorrhage is low. Coblation tonsillectomy and less than 5 years’ experience of surgeon contribute to the tendency for primary hemorrhage. Age and time of onset are responsible for secondary hemorrhage.

Locally administered heparin-binding epidermal growth factor-like growth factor reduces radiation-induced oral mucositis in mice

Oral mucositis refers to lesions of the oral mucosa observed in patients with cancer being treated with radiation with or without chemotherapy, and can significantly affect quality of life. There is a large unmet medical need to prevent oral mucositis that can occur with radiation either alone or in combination with chemotherapy. We investigated the efficacy of locally administered heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent epithelial proliferation and migration stimulator of the oral mucosa as a potential therapy to prevent radiation induced oral mucositis. Using a single dose (20 Gy) of radiation to the oral cavity of female C57BL/6 J mice, we evaluated the efficacy of HB-EGF treatment (5 µl of 10 µg/ml) solution. The results show that HB-EGF delivered post radiation, significantly increased the area of epithelial thickness on the tongue (dorsal tongue (42,106 vs 53,493 µm2, p < 0.01), ventral tongue (30,793 vs 39,095 µm2, *p < 0.05)) compared to vehicle control, enhanced new epithelial cell division, and increased the quality and quantity of desmosomes in the oral mucosa measured in the tongue and buccal mucosa. This data provides the proof of concept that local administration of HB-EGF has the potential to be developed as a topical treatment to mitigate oral mucositis following radiation.

Hyaluronan/collagen hydrogels containing sulfated hyaluronan improve wound healing by sustained release of heparin-binding EGF-like growth factor

Functional biomaterials that are able to bind, stabilize and release bioactive proteins in a defined manner are required for the controlled delivery of such to the desired place of action, stimulating wound healing in health-compromised patients. Glycosaminoglycans (GAG) represent a very promising group of components since they may be functionally engineered and are well tolerated by the recipient tissues due to their relative immunological inertness. Ligands of the Epidermal Growth Factor (EGF) receptor (EGFR) activate keratinocytes and dermal fibroblasts and, thus, contribute to skin wound healing. Heparin-binding EGF-like growth factor (HB-EGF) bound to GAG in biomaterials (e.g. hydrogels) might serve as a reservoir that induces prolonged activation of the EGF receptor and to recover disturbed wound healing. Based on previous findings, the capacity of hyaluronan (HA) and its sulfated derivatives (sHA) to bind and release HB-EGF from HA/collagen-based hydrogels was investigated. Docking and molecular dynamics analysis of a molecular model of HB-EGF led to the identification of residues in the heparin-binding domain of the protein being essential for the recognition of GAG derivatives. Furthermore, molecular modeling and surface plasmon resonance (SPR) analyses demonstrated that sulfation of HA increases binding strength to HB-EGF thus providing a rationale for the development of sHA-containing hydrogels. In line with computational observations and in agreement with SPR results, gels containing sHA displayed a retarded HB-EGF release in vitro compared to pure HA/collagen gels. Hydrogels containing HA and collagen or a mixture with sHA were shown to bind and release bioactive HB-EGF over at least 72 h, which induced keratinocyte migration, EGFR-signaling and HGF expression in dermal fibroblasts. Importantly, hydrogels containing sHA strongly increased the effectivity of HB-EGF in inducing epithelial tip growth in epithelial wounds shown in a porcine skin organ culture model. These findings suggest that hydrogels containing HA and sHA can be engineered for smart and effective wound dressings. STATEMENT OF SIGNIFICANCE: Immobilization and sustained release of recombinant proteins from functional biomaterials might overcome the limited success of direct application of non-protected solute growth factors during the treatment of impaired wound healing. We developed HA/collagen-based hydrogels supplemented with acrylated sulfated HA for binding and release of HB-EGF. We analyzed the molecular basis of HB-EGF interaction with HA and its chemical derivatives by in silico modeling and surface plasmon resonance. These hydrogels bind HB-EGF reversibly. Using different in vitro assays and organ culture we demonstrate that the introduction of sulfated HA into the hydrogels significantly increases the effectivity of HB-EGF action on target cells. Therefore, sulfated HA-containing hydrogels are promising functional biomaterials for the development of mediator releasing wound dressings.