What Is Crohn's Disease?

Crohn's disease is a lifelong inflammatory bowel disease with no cure, managed today through a combination of medications, lifestyle support, and — for many patients — surgery. This article explains what causes it, how it presents, how doctors treat it now, and where cell-based research stands, including the one cell therapy that has actually cleared a major regulatory bar for a Crohn's-related complication, and the important caveats around where it is and isn't available.

What Is Crohn's Disease?

Crohn's disease is a chronic inflammatory bowel disease (IBD) that can affect any part of the digestive tract, from the mouth to the anus, though it most often involves the end of the small intestine and the beginning of the colon. Unlike ulcerative colitis, which stays confined to the colon's inner lining, Crohn's inflammation can extend through the full thickness of the bowel wall. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the exact cause is unknown, but research points to a combination of genetics, an abnormal immune response, and disruptions in the gut microbiome. It's most commonly diagnosed between ages 20 and 29, though it can appear at any age. Federal survey data from 2023-2024 put diagnosed Crohn's disease at about 0.5% of U.S. adults — roughly 1.3 million people — within a broader IBD population of about 4.1 million Americans.

Symptoms and Complications

Symptoms vary and typically follow a relapsing-remitting course, with flares interspersed by periods of relative quiet. Common symptoms include persistent diarrhea, abdominal cramping and pain, unintended weight loss, fatigue, and reduced appetite. Over time, chronic inflammation can lead to complications: strictures (narrowed, scarred segments of bowel), abscesses, malnutrition, and fistulas — abnormal tunnels that form between the bowel and nearby organs or skin. Perianal fistulas, which connect the bowel to the skin near the anus, are among the most difficult Crohn's complications to treat and a major focus of the cell-therapy research discussed below.

How Crohn's Is Diagnosed and Treated Today

There's no single test for Crohn's; diagnosis relies on a combination of medical history, blood and stool tests, endoscopy with biopsy, and cross-sectional imaging. Treatment goals are to reduce inflammation, induce remission, and keep the disease quiet over the long term. Standard medical therapy progresses through several classes: anti-inflammatory drugs and corticosteroids for flares, immunomodulators (such as azathioprine or methotrexate) to tamp down immune activity, and biologics — anti-TNF drugs, anti-integrin agents, and IL-12/23 inhibitors — for moderate-to-severe or refractory disease. Nutritional support is often part of care as well. Even with modern biologics, a substantial share of Crohn's patients eventually need surgery to remove damaged bowel, drain abscesses, or repair fistulas — but surgery doesn't cure the disease, and recurrence at or near the surgical site is common. For complex perianal fistulas specifically, response to standard medical and surgical treatment is often poor, which is exactly the gap cell therapy research has tried to address.

Where Stem Cell and Cell Therapy Research Stands

This is where Crohn's disease occupies an unusual place in regenerative medicine: it's connected to one of the few cell therapies to actually reach regulatory approval for any indication tied to the disease. Darvadstrocel (brand name Alofisel), made from expanded allogeneic mesenchymal stem cells derived from donor fat tissue, is injected directly into complex perianal fistula tracts in adults with Crohn's disease. In its pivotal ADMIRE-CD trial, about half of treated patients achieved combined remission at 24 weeks, compared with roughly a third on placebo — results the European Medicines Agency judged clinically meaningful in patients who had already failed other options. The EMA approved Alofisel in March 2018, and for years it was marketed in the EU, UK, Switzerland, Israel, and Japan.

It was never approved in the United States, however. A larger confirmatory trial Takeda ran specifically to support a U.S. filing, ADMIRE-CD II, missed its primary endpoint in 2023 — combined remission was statistically indistinguishable from placebo. And in December 2024, the European Commission withdrew Alofisel's EU marketing authorization at Takeda's request, ending its availability in the market where it had been approved longest. The net picture today: a cell therapy for Crohn's-related perianal fistulas has cleared regulatory review before, with real trial data behind it, but none is currently approved or marketed anywhere, and none has ever been approved in the U.S. Beyond fistula-directed therapy, researchers have also studied systemic mesenchymal stem cell infusions and, in a small number of severe, treatment-refractory cases, hematopoietic stem cell transplantation — but these remain investigational, early-stage, and outside standard care. RegenMed Review covers the underlying clinical trial evidence for Crohn's and perianal fistula cell therapy in more depth elsewhere on the site.

Bottom Line

Crohn's disease remains a chronic, relapsing condition without a cure, and standard treatment — medication to control inflammation plus surgery when needed — still leaves many patients, especially those with complex perianal fistulas, without a durable fix. Cell therapy research has produced one of the field's clearest regulatory milestones in darvadstrocel, but its unwinding in Europe and failure to win U.S. approval is a useful reminder that early approval success doesn't guarantee a treatment stays available, or works, as later evidence accumulates. For now, stem cell approaches to Crohn's disease remain an active, promising, but still unsettled area of research rather than a mainstream option.