P-248 Fallopian tube extracellular matrix hydrogels for in vitro embryo culture in rabbit models: A post-natal study
Authors: Francés E , Marco-Jiménez F , Faus A , Vicente J.S , Cervelló I 
Published: June 2022

Abstract

Study question
Can tissue-specific extracellular matrix (ECM) hydrogels derived from decellularized (DC) fallopian tubes have phenotypic consequences in the offspring when used for in vitro embryo culture?

Summary answer
Tissue-specific ECM hydrogels from DC rabbit fallopian tubes influence assisted reproductive technologies (ART) outcomes, resulting in offspring with a higher body weight.

What is known already
The in vitro culture of embryos fails to mimic the physiological dynamism occurring in the reproductive tract. In response to this sub-optimal environment, mammalian embryo exhibits a high degree of developmental plasticity, leading to specific phenotypic deviations at birth and beyond (e.g. low weight). Recently, it has been demonstrated that using in vivo derived culture complements, these changes can be ameliorated. The ECM is one of the elements shown to be important in retaining structural and biological signals from the native source tissue. The current bioengineering techniques could provide hydrogels mimicking the native environment and offering an optimal embryo development.

Study design, size, duration
This study was approved by an ethics committee (2018/VSC/PEA/0116). Rabbit oviducts (n = 24) were collected, fragmented, DC and solubilized to create hydrogels. After physicochemical characterization, the tissue-specific ECM hydrogels were used for in vitro culture of pronuclear embryos during 48 hours (n = 146), which were subsequently transferred to recipient females, along with embryos cultured under control conditions (n = 138). After delivery, the rabbits were weighed during 20 weeks and blood tests were performed at weeks 8 and 20.

Participants/materials, setting, methods
To create hydrogels, we employed a decellularization protocol based on SDS detergent. After characterizing and validating decellularization (Francés-Herrero et al. 2021), ECM hydrogels were used to generate coatings (overnight at 37ºC) on culture plates. Pronuclear embryos were cultured until morula stage and then transferred by laparoscopy to obtain the offspring. The animals were weighed and their blood was analyzed by hemogram. T-test was used for the statistical analysis after normality verification (p &lt; 0.05 statistically significant).

Main results and the role of chance
After 48 hours of embryo culture, no differences in development and morphology were detected between the coating and control conditions (Francés-Herrero et al. 2021). With a total of 284 embryos transferred, the implantation and live birth rates were slightly higher in the coating group than in the control group (31.26 ± 21.44% vs 26.53 ± 24.8% and 19.96 ± 12.5% vs 18.68 ± 24.68%, respectively), but the differences were not statistically significant. During the first 20 weeks of life, the animals from the coating group consistently showed higher weights than the control group. Although this difference was not significant at birth (75.15 ± 15.48 g vs 61.88 ± 17.79 g, respectively), it was significant at subsequent measurements (1117.73 ± 172.54 g vs 942 ± 105.51 g at week 5, 2513 ± 352.83 g vs 2256.25 ± 168.52 g at week 10, 3475.56 ± 297.91 g vs 3257.5 ± 189.94 g; at week 15 and 4151.11 ± 269.28 g vs 3808.75 ± 293.08 g at week 20; p &lt; 0.05). The animals of both experimental groups showed normal blood parameters (white blood cells, % lymphocytes, % monocytes, % granulocytes, red blood cells and hematocrit) at 8 and 20 weeks of life.

Limitations, reasons for caution
This study has been carried out in an animal model and, although the offspring generated is healthy, the scope of this technique is still unknown. So, the next step would be to study the embryonic reprogramming or media metabolomic profile under ECM in vitro culture.

Wider implications of the findings
These findings show how culture media supplementation with fallopian tube ECM allows improving in vitro conditions and decreases postnatal phenotypic deviations after ART. This study could initiate a new embryo culture techniques era to guarantee that ART are utilized in the most efficient and safest possible practice.

Trial registration number
Not applicable