Japan's Fast Lane for Regenerative Medicine — and Why America Still Waits

In December 2018, a Japanese man with a spinal cord injury received an infusion of his own bone-marrow stem cells — not as part of a clinical trial he had to qualify for, but as an approved, insurance-covered medical treatment. In the United States, the same therapy exists only inside investigational protocols. An American in his situation could, at best, enroll in a Phase 1 trial and hope to be randomized to the treatment arm.

The therapy is called Stemirac, made by the Japanese medical device company Nipro, and it is one of the clearest examples of a regulatory idea Japan has been testing for over a decade: approving certain regenerative medicine products for real-world use based on early signs of safety and “probable” benefit, then requiring years of follow-up data to prove the therapy actually works.

How Japan’s system works

The pathway dates to 2014, when Japan’s Pharmaceuticals and Medical Devices (PMD) Act created a conditional and time-limited approval (CEA) track specifically for regenerative medical products — treatments built from cells, tissues, or genes. Under this track, a company can win market approval by demonstrating safety and a plausible clinical benefit, even from a small, uncontrolled study. Once approved, the product goes on sale, national health insurance covers it, and patients can receive it as ordinary care — while the manufacturer runs a larger post-marketing study, typically over several years, to confirm it actually helps.

Stemirac’s own approval rested on a trial of just 13 patients, 12 of whom improved by at least one grade on a standard spinal-cord-injury impairment scale. That would not be nearly enough evidence for standard U.S. approval. In Japan, it was enough to bring the therapy to market while the harder proof was still being gathered.

Where the United States stands

As of 2025, there is no FDA-approved stem cell therapy for spinal cord injury anywhere in the U.S. market. Several are in active investigation — including iPSC-derived cell therapies that only received FDA clearance to begin Phase 1 trials in 2025 — but American patients with spinal cord injuries today have no legal path to a cell-based treatment outside of a research study. The FDA’s standard for cell and gene therapies generally requires larger, controlled trials with statistically confirmed efficacy before a product can reach the market — a higher, slower bar than Japan’s conditional pathway.

A system that admits its own uncertainty

What makes Japan’s approach notable is that it doesn’t pretend the trade-off is free. The same conditional pathway that brought Stemirac to patients also approved HeartSheet, a Terumo-made sheet of a patient’s own skeletal muscle cells, for advanced heart failure — based on a single-center trial of just seven patients in 2015. Nearly a decade later, in July 2024, the mandated post-marketing study of over 150 patients found that HeartSheet neither improved survival nor strengthened heart function compared with standard care. Japan’s health ministry withdrew its approval, and Terumo stopped selling it immediately.

That outcome is, in a sense, the system working as designed: it let real patients access a promising therapy years earlier than a conventional trial timeline would have allowed, and it built in a mechanism to pull the therapy back once the evidence came in against it. The U.S. system optimizes for certainty before access; Japan’s optimizes for access while chasing certainty. Neither is simply right or wrong — they reflect different judgments about how much unproven promise a healthcare system should be willing to extend to patients who have few other options.

Why this gap exists

Part of the answer is philosophical. Japanese healthcare has long leaned toward proactive intervention — the same instinct that fills Ningen Dock screening clinics with people checking for disease before symptoms appear also underlies a willingness to let patients try a plausible treatment earlier, under close observation. The American system, shaped by decades of drug-safety history, leans the other way: prove it thoroughly, then release it.

For patients facing conditions with no good options, that philosophical difference has very real consequences for what’s available to them, and when.

Sources:

• Global Focus: Japan’s Regenerative Medicine Regulatory Pathways — Food and Drug Law Institute
• Japan’s Conditional/Time-Limited Early Approval System in Regenerative Medicine: A Case Study of Rise and Falls of Autologous Skeletal Myoblast Sheets — PMC
• Japan’s approval of stem-cell treatment for spinal-cord injury concerns scientists — PubMed
• Current Landscape of FDA Stem Cell Approvals and Trials 2023-2025 — Reprocell