Isolation, identification and culture of myenteric plexus cells from ovine esophagus

Esophagus stretch tests: Biomechanics for tissue engineering and possible implications on the outcome of esophageal atresia repairs performed under excessive tension

BACKGROUND

Esophageal biomechanical studies are important to understand structural changes resulting from stretches during repair of esophageal atresias as well as to obtain values to compare with the biomechanics of tissue-engineered esophagus in the future. This study aimed to investigate light microscopic changes after uniaxial stretching of the ovine esophagus.

METHODS

In vitro uniaxial stretching was performed on esophagi (n = 20) of 1-month-old lambs within 4-6 h post-mortem. Esophagi were divided into 5 groups: control and stretched (1.1, 1.2, 1.3 and 1.4). Force and lengthening were measured with 5 cycles performed on every specimen using a PBS organ bath at 37 °C. Histological studies were performed on the 5 groups.

RESULTS

Low forces of ~ 2 N (N) were sufficient for a 1.2-1.25 stretch in the 1st cycle, whereas a three times higher force (~ 6 N) was needed for a stretch of 1.3. In the 2nd to 5th cycle, the tissue weakened and a force of ~ 3 N was sufficient for a stretch of 1.3. Histologically, in the 1.3-1.4 stretch groups, rupture of muscle fibers and capillaries were observed, respectively. Changes in mucosa and collagen fibers could not be observed.

CONCLUSIONS

These results offer norm values from the native esophagus to compare with the biomechanics of future tissue-engineered esophagus. Esophageal stretching > 1.3 leads to tears in muscle fibers and to rupture of capillaries. These findings can explain the decrease in microcirculation and scarring in mobilized tissue and possibly offer clues to impaired motility in esophagus atresias repaired under excessive tension.

Comparison of esophageal submucosal glands in experimental models for esophagus tissue engineering applications

OBJECTIVE

Esophagus tissue engineering holds promises to overcome the limitations of the presently employed esophageal replacement procedures. This study investigated 5 animal models for esophageal submucosal glands (ESMG) to identify models appropriate for regenerative medicine applications. Furthermore, this study aimed to measure geometric parameters of ESMG that could be utilized for fabrication of ESMG-specific scaffolds for esophagus tissue engineering applications.

METHODS

Ovine, avian, bovine, murine, and porcine esophagus were investigated using Hematoxylin-Eosin (HE), Periodic Acid Schiff (PAS), and Alcian Blue (AB), with AB applied in 3 pH levels (0.2, 1.0, and 2.5) to detect sulphated mucous. Celleye^® (version F) was employed to gain parametric data on ESMGs (size, perimeter, distance to lumen, and acini concentration) necessary for scaffold fabrication.

RESULTS

Murine, bovine, and ovine esophagus were devoid of ESMG. Avian esophagus demonstrated sulphated acid mucous producing ESMGs with a holocrine secretion pattern, whereas sulphated acid and neutral mucous producing ESMGs with a merocrine secretion pattern were observed in porcine esophagus. Distance of ESMGs to lumen ranged from 127-340 μm (avian) to 916-983 μm (porcine). ESMGs comprised 35% (avian) to 45% (porcine) area of the submucosa. ESMG had an area of 125000 μm² (avian) to 580000 μm² (porcine).

CONCLUSION

Avian and porcine esophagus possesses ESMGs. However, porcine esophagus correlates with data available on human ESMGs. Geometric and parametric data obtained from ESMG are valuable for the fabrication of ESMG-specific scaffolds for esophagus tissue engineering using the hybrid construct approach.

Bioengineering the gut: future prospects of regenerative medicine

Functions of the gastrointestinal tract include motility, digestion and absorption of nutrients. These functions are mediated by several specialized cell types including smooth muscle cells, neurons, interstitial cells and epithelial cells. In gastrointestinal diseases, some of the cells become degenerated or fail to accomplish their normal functions. Surgical resection of the diseased segments of the gastrointestinal tract is considered the gold-standard treatment in many cases, but patients might have surgical complications and quality of life can remain low. Tissue engineering and regenerative medicine aim to restore, repair, or regenerate the function of the tissues. Gastrointestinal tissue engineering is a challenging process given the specific phenotype and alignment of each cell type that colonizes the tract - these properties are critical for proper functionality. In this Review, we summarize advances in the field of gastrointestinal tissue engineering and regenerative medicine. Although the findings are promising, additional studies and optimizations are needed for translational purposes.