A rat uterine horn model of genital tract wound healing

The effects of oestrogen on vaginal wound healing: A systematic review and meta-analysis

Aims

To determine the effects of oestrogen or oestrogen deprivation on vaginal wound healing. Impaired wound healing following prolapse surgery may increase the risk of recurrent prolapse in the future. Vaginal oestrogen therapy may improve wound healing, hereby possibly improving surgical outcomes.

Methods

A systematic search of OVID MEDLINE, OVID Embase, and Web of Science was conducted up to January 28, 2020. We included original studies comparing wound healing‐related outcomes of oestrogen exposed subjects (female animals and women) to hypo‐oestrogenic subjects after vaginal surgery. Data on wound healing‐related outcome measures were extracted. For each individual comparison, the standardised mean difference (Hedges' g; SMD) and 95% confidence interval (CI) were calculated.

Results

Of the 1474 studies reviewed, 14 studies were included for review, and 11 provided data for meta‐analysis. Oestrogen improves neovascularisation (SMD: 1.13, 95% CI: 0.67–1.60), microscopic wound closure (SMD: 0.98, 95% CI: 0.66–1.29), collagen synthesis (SMD: 1.08, 95% CI: 0.42–1.74), and tissue strength (SMD: 1.26, 95% CI: 0.53–1.99) in animals. Oestrogen increases granulation (SMD: 1.67, 95% CI: 0.54–2.79) and accelerates macroscopic wound closure (SMD: 1.82, 95% CI: 1.22–2.42) in women and animals. Oestrogen decreases the inflammatory response (SMD: −0.58, 95% CI: −1.14 to −0.02) in women and animals and reduces levels of transforming growth factor (TGF)‐β1 (SMD: −1.68, 95% CI: −2.52 to −0.83) in animals. All results were statistically significant.

Conclusions

Oestrogen therapy has a positive effect on vaginal wound healing. Future studies should determine whether oestrogen therapy has the potential to improve surgical outcomes.

Estrogen alters remodeling of the vaginal wall after surgical injury in guinea pigs

Loss of pelvic organ support (i.e., pelvic organ prolapse) is common in menopausal women. Surgical reconstruction of pelvic organ prolapse is plagued with high failure rates. The objective of this study was to determine the effects of estrogen on biomechanical properties, lysyl oxidase (LOX), collagen content, and histomorphology of the vagina with or without surgical injury. Nulliparous ovariectomized guinea pigs were treated systemically with either 50 μg/kg/day estradiol (E2,) or vehicle. After 2 wk, vaginal surgery was performed, and animals were treated with either beta-aminopropionitrile (BAPN, an irreversible LOX inhibitor), or vehicle to determine the role of LOX in recovery of the vaginal wall from injury with or without E2. Estradiol resulted in (i) significant growth, increased smooth muscle, and increased thickness of the vagina, (ii) increased distensibility without compromise of maximal force at failure, and (iii) increased total and cross-linked collagen. In the absence of E2, BAPN resulted in decreased collagen and vaginal wall strength in the area of the injury. In contrast, in E2-treated animals, increased distensibility, maximal forces, and total collagen were maintained despite BAPN. Interestingly, LOX mRNA was induced dramatically (9.5-fold) in the injured vagina with or without E2 at 4 days. By 21 days, however, LOX levels declined to near baseline in E2-deprived animals. LOX mRNA levels remained strikingly elevated (12-fold) at 21 days in the estrogenized vagina. The results suggest that prolonged E2 induced increases in LOX, and collagen cross-links may act to sustain a matrix environment that optimizes long-term surgical wound healing in the vagina.

Transforming growth factor beta1 gene expression during vaginal wound healing in a rabbit menopause model

OBJECTIVE

Surgical outcome following reconstructive pelvic surgery is largely dependent on the vaginal wound healing process. As peri- and post-menopausal women are the most likely candidates to undergo these surgeries, it is important to understand the effect of estrogen deficiency on this process. Transforming growth factor beta (TGFβ) is an important mediator of wound healing. We sought to assess TGFβ1 gene expression during the vaginal incisional wound healing process in a rabbit menopause model.

DESIGN

Animal study.

SETTING

Animal laboratory.

SAMPLE

Sixty-three rabbits were used for this study.

METHODS

Twenty-one underwent bilateral oophorectomy, 21 underwent a sham surgery, and 21 served as controls. Eight weeks later, standardised full-thickness 6-mm diameter circular segments were excised from the vagina of all rabbits. Animals were killed sequentially, before wounding, and at 0, 4, 7, 14, 21 and 35 days after wounding, and the wounds were harvested.

MAIN OUTCOME MEASURES

Wound closure and TGFβ1 gene transcription, as measured by real-time polymerase chain reaction (PCR).

RESULTS

Wound closure was significantly protracted (P < 0.02), whereas TGFβ1 gene expression was significantly increased (P < 0.0001) during the wound healing process in oophorectomised rabbits, as compared with both control and sham groups.

CONCLUSION

Oophorectomised rabbits show protracted incisional vaginal wound healing associated with increased TGFβ1 gene transcription.

Effect of bilateral oophorectomy on wound healing of the rabbit vagina

We aimed to assess the effect of bilateral oophorectomy on vaginal wound healing in three groups of New Zealand White rabbits (24 rabbits each). Group 1 underwent bilateral oophorectomy, group 2 underwent a sham surgery, and group 3 served as control. Standardized vaginal tissue specimens were harvested and assessed for wound and scar surface area and tensiometric analysis before wounding, and sequentially thereafter, showing that vaginal wound closure, scar contraction, and recovery of biomechanical properties are significantly slower in oophorectomized rabbits.

Estrogen replacement therapy and the surgeon

BACKGROUND

The number of patients over the age of 65 years has increased to 33.2 million, with a life expectancy of 76.5 years. With an aging population, the number of surgical procedures is expected to increase as much as 50%. The majority of individuals over 65 years are women. Estrogen replacement therapy is commonly recommended to postmenopausal women for relief of vasomotor symptoms, protection against heart disease, and prevention of osteoporosis.

PURPOSE

The purpose of this review is to address estrogen replacement therapy with regard to wound healing, fracture repair, perioperative cardiac morbidity, and thrombosis.

DATA SOURCE

Medline Literature review.

CONCLUSIONS

There is insufficient evidence to withdraw estrogen replacement therapy at the time of admission for surgery. Patients not receiving estrogen replacement therapy should be offered therapy upon return to ambulatory status.

Oestrogens and wound healing

During the past few decades several studies have documented the deleterious impact of the menopause on bone mass and cardiovascular disease, and the reduction of risk in this area by HRT. However, the possible effects of the postmenopausal deficiency in ovarian hormones on skin and its repair post-injury, are less well documented. This review provides a survey of the literature that is available regarding the involvement and influence of oestrogens on the various phases of cutaneous repair - inflammation, proliferation and remodelling. Research carried out on the effects of oestrogens, both in terms of deficiency and replacement, on the process of wound healing in various animal models is described and discussed, together with the very limited work undertaken in humans. This area of research is of paramount clinical importance both in terms of financial cost and human suffering, since many chronic wounds such as venous ulcers, pressure sores and burns afflict the elderly population, of whom postmenopausal women comprise the majority. Clinically our aim should be to restore the integrity and function of wounded tissue as rapidly as possible after injury and it is generally believed that a better understanding of the effects of oestrogens on wound healing could lead to improved care of cutaneous wounds, and the treatment of not only the wound but of the postmenopausal woman as a whole.

Impairment of granulation tissue formation after menopause

Formation of connective tissue is an essential step in the process of wound healing. After menopause an atrophy of connective tissues in skin, bone, and reproductive organs takes place. Using a dead-space wound healing model we measured collagen synthesis and deposition, and cell replication in the granulation tissue of 18 premenopausal and 23 peri- and postmenopausal women not receiving any hormonal therapy. In the postmenopausal group collagen synthesis and deposition and cell number in the granulation tissue were diminished. These results document the impairment of the granulation tissue formation after menopause.

Comparative functional study of Dexon and nylon microsutures in rat uterine anastomoses

Forty-two female Wistar rats were used in a long-term study designed to evaluate the functional sequelae of employing 10-0 Dexon "S" and nylon microsutures in uterine anastomoses. Functional criteria used were the number of fetuses and live births, during and after pregnancy, respectively. Results indicate that the rats from both control and experimental groups were likely to have identical litter sizes for the first 3 deliveries (P greater than 0.01). An unexplained observation was the finding of a larger litter size for the experimental group rats at the fourth delivery as compared to its control counterpart (P less than 0.01). Also explicit is the propensity for the right uterine horn to bear a larger number of fetuses than its counterpart (P less than 0.01). Finally, neither suture was associated with a larger number of fetuses (P greater than 0.01). It was concluded that 1) uterine anastomosis did not prove detrimental to the functional outcome, 2) none of the sutures proved functionally superior, and 3) nylon was more likely to be associated with foreign body and inflammatory responses.