Amniotic Membrane Restores Chronic Wound Features to Normal in a Keratinocyte TGF-ß-Chronified Cell Model.

Unsuccessful wound closure in chronic wounds can be linked to altered keratinocyte activation and their inability to re-epithelize. Suggested mechanisms driving this impairment involve unbalanced cytokine signaling. However, the molecular events leading to these aberrant responses are poorly understood. Among cytokines affecting keratinocyte responses, Transforming Growth Factor-ß (TFG-ß) is thought to have a great impact. In this study, we have used a previously characterized skin epidermal in vitro model, HaCaT cells continuously exposed to TGF-ß1, to study the wound recovery capabilities of chronified/senescent keratinocytes. In this setting, chronified keratinocytes show decreased migration and reduced activation in response to injury. Amniotic membrane (AM) has been used successfully to manage unresponsive complicated wounds. In our in vitro setting, AM treatment of chronified keratinocytes re-enabled migration in the early stages of wound healing, also promoting proliferation at later stages. Interestingly, when checking the gene expression of markers known to be altered in TGF-ß chronified cells and involved in cell cycle regulation, early migratory responses, senescence, and chronic inflammation, we discovered that AM treatment seemed to reset back to keratinocyte status. The analysis of the evolution of both the levels of keratinocyte activation marker cytokeratin 17 and the spatial-temporal expression pattern of the proliferation marker Ki-67 in human in vivo biopsy samples suggests that responses to AM recorded in TGF-ß chronified HaCaT cells would be homologous to those of resident keratinocytes in chronic wounds. All these results provide further evidence that sustained TGF-ß might play a key role in wound chronification and postulate the validity of our TGF-ß chronified HaCaT in vitro model for the study of chronic wound physiology.

Chronic Wound Healing by Amniotic Membrane: TGF-ß and EGF Signaling Modulation in Re-epithelialization.

The application of amniotic membrane (AM) on chronic wounds has proven very effective at resetting wound healing, particularly in re-epithelialization. Historically, several aspects of AM effect on wound healing have been evaluated using cell models. In keratinocytes, the presence of AM induces the activation of mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK) pathways, together with the high expression of c-Jun, an important transcription factor for the progression of the re-epithelialization tongue. In general, the levels of transforming growth factor (TGF)-ß present in a wound are critical for the process of wound healing; they are elevated during the inflammation phase and remain high in some chronic wounds. Interestingly, the presence of AM, through epidermal growth factor (EGF) signaling, produces a fine-tuning of the TGF-ß signaling pathway that re-conducts the stalled process of wound healing. However, the complete suppression of TGF-ß signaling has proven negative for the AM stimulation of migration, suggesting that a minimal amount of TGF-ß signaling is required for proper wound healing. Regarding migration machinery, AM contributes to the dynamics of focal adhesions, producing a high turnover and thus speeding up remodeling. This is clear because proteins, such as Paxillin, are activated upon treatment with AM. On top of this, AM also produces changes in the expression of Paxillin. Although we have made great progress in understanding the effects of AM on chronic wound healing, a long way is still ahead of us to fully comprehend its effects.

Prophylactic Use of Negative Pressure Therapy in General Abdominal Surgery: A Systematic Review and Meta-Analysis.

Background: Surgical site infections (SSIs) represent an economic burden to healthcare systems. The use of negative pressure wound therapy (NPWT) for SSI prophylaxis remains uncertain. Methods: A systematic literature search was conducted in Medline/PubMed, CINAHL, and Web of Science for relevant studies. The primary outcome was the evaluation of the effectiveness of NPWT for prophylaxis of SSI rates in general abdominal surgery. Secondary outcomes were rates of seroma and wound dehiscence, length of hospital stay, and re-admission rates. The statistical analysis was performed with random effect models. Results: A total of 3,193 patients from 20 articles (six randomized controlled trials [RCT], three prospective, eight retrospective, and three ambispective studies) were analyzed. Negative pressure wound therapy was associated with decreased rate of SSIs compared with standard dressing in a pooled analysis of non-randomized studies and RCTs (0.57; 95% confidence interval [CI], -0.4 to 0.8; p < 0.001). This result, however, needs to be challenged because of a significant statistical heterogeneity of the included studies (I2 = 71%; p < 0.01). A separate analysis of the six RCTs failed to confirm the superiority of NPWT (0.64; 95% CI, -0.4 to 1.04; p = 0.07), also disclosing significant heterogeneity. The analysis of secondary outcomes was only possible in combination of randomized and non-randomized studies because of incomplete datasets in RCTs. Re-admission rates were lower after NPWT and no difference was observed for the incidence of seroma, wound dehiscence, and length of hospital stay. Conclusions: Based on available evidence, the routine use of NPWT for SSI prophylaxis after laparotomy in general abdominal surgery cannot be generally recommended.

Use of cryopreserved human amniotic membrane in the treatment of skin ulcers secondary to calciphylaxis.

Calciphylaxis is a rare condition characterized by skin ulceration and necrosis as a result of vascular calcification of the small and medium blood vessels of skin and subcutaneous tissues. It mainly occurs in patients with advanced chronic kidney disease and sometimes leads to complications with a fatal outcome. In this report, we describe the case of a 67-year-old male patient with end stage renal disease presenting painful skin ulcers on his lower limbs. The lesions had progressively grown and were associated to severe pain and decreased quality of life. The ulcers did not respond to conventional treatments and the patient underwent skin biopsy of these lesions obtaining anatomopathological findings compatible with calciphylaxis. In this report, we present an innovative treatment for skin ulcers secondary to calciphylaxis using cryopreserved amniotic membrane (AM) as a dressing in order to promote epithelialization of the wounds. After four applications, healing of the main ulcer and reduction in pain was achieved. In summary, applying cryopreserved AM probed to be a promising strategy to reduce pain and to enhance epithelialization and healing of chronic non-responsive ulcers in calciphylaxis.