Bioengineered intestinal muscularis complexes with long-term spontaneous and periodic contractions

Abstract

Although critical for studies of gut motility and intestinal regeneration, the in vitro culture of intestinal muscularis with peristaltic function remains a significant challenge. Periodic contractions of intestinal muscularis result from the coordinated activity of smooth muscle cells (SMC), the enteric nervous system (ENS), and interstitial cells of Cajal (ICC). Reproducing this activity requires the preservation of all these cells in one system. Here we report the first serum-free culture methodology that consistently maintains spontaneous and periodic contractions of murine and human intestinal muscularis cells for months. In this system, SMC expressed the mature marker myosin heavy chain, and multipolar/dipolar ICC, uniaxonal/multipolar neurons and glial cells were present. Furthermore, drugs affecting ENS, ICC or SMC altered the contractions. Combining this method with scaffolds, contracting cell sheets were formed with organized architecture. With the addition of intestinal epithelial cells, this platform enabled at least 9 types of cells from mucosa and muscularis to coexist and function. The method constitutes a powerful tool for mechanistic studies of gut motility disorders and the regeneration of full-thickness engineered intestine.\n\nIn the small intestine, the mucosa processes partially digested food and absorbs nutrients while the muscularis actuates the peristaltic flow to transport luminal content aborally. Gut motility is central to its digestive and absorptive function. The intestinal muscularis contains various types of cells: of these, smooth muscle cells, the enteric nervous system (ENS)1,2, and the pacemaker interstitial cells of Cajal (ICC)3 are three important players involved in the development of gut motility. Recent studies on intestinal tissue engineering have highlighted the importance of regenerating the functional intestinal muscularis4-9. A variety of systems derived from different cell sources, including pluripotent stem cells (PSC)4-6, embryonic stem cells (ESC)7 and primary tissue8,9, have been established to accomplish this goal and different contractile activities were developed in these systems. Notably, spontaneous contractions have been generated in culture systems that contained both ICC and smooth muscle cells4,6,10-13. In addition, electrical-induced neurogenic contractions were also successfully produced4,5,8 when ENS was introduced into culture. In one of the most recent studies, both spontaneous contractions and electrical-induced neurogenic contractions were developed in a PSC-based culture system4.