Elon Musk's Neuralink received US Food and Drug Administration (FDA) clearance for its first-in-human clinical trial, a critical milestone for the brain-implant startup as it faces US probes over its handling of animal experiments.
The FDA approval "represents an important first step that will one day allow our technology to help many people," Neuralink said in a tweet, without disclosing details of the planned study.
It added it is not recruiting for the trial yet and said more details would be available soon.
The FDA acknowledged in a statement that the agency cleared Neuralink to use its brain implant and surgical robot for trials on patients but declined to provide more details.
Neuralink and Musk did not respond to Reuters requests for comment.
The critical milestone comes as Neuralink faces federal scrutiny following Reuters reports about the company's animal experiments.
Neuralink employees told Reuters last year that the company was rushing and botching surgeries on monkeys, pigs and sheep, resulting in more animal deaths than necessary, as Musk pressured staff to receive FDA approval.
The animal experiments produced data intended to support the company's application for human trials, the sources said.
In one instance in 2021, the company implanted 25 out of 60 pigs with the wrong-sized devices.
All the pigs were subsequently killed - an error that employees said could have been easily avoided with more preparation.
In May, US lawmakers urged regulators to investigate whether the makeup of a panel overseeing animal testing at Neuralink contributed to botched and rushed experiments after Reuters reported on potential financial conflicts on the panel.
The Department of Transportation is separately probing whether Neuralink illegally transported dangerous pathogens on chips removed from monkey brains without proper containment measures.
Neuralink is also under investigation by the US Department of Agriculture's Office of Inspector General for potential animal-welfare violations.
This probe has been looking at the USDA's oversight of Neuralink.
The probe was launched amid growing employee concern that the company is rushing experiments, causing additional suffering and deaths of pigs, sheep and monkeys.
Neither Musk nor Neuralink ever responded to multiple requests for comment on the Reuters reports.
As of several weeks ago, the FDA had not inspected Neuralink over its laboratory practices, according to FDA records and a Neuralink employee.
Victor Krauthamer, an adjunct biomedical engineering professor who spent three decades at the FDA, including a stint overseeing the office that reviews human-trial requests for brain implants, said the FDA does not typically inspect facilities as part of their review of applications for clinical trials.
But he added this would have been warranted in this case, given the concerns around Neuralink's animal experiments.
"If the animal testing is unreliable, then (human trial) approval may be based on flawed animal safety data. The FDA should have verified their trust of animal study results," Krauthamer said.
Neuralink had hoped to receive approval to implant its device in 10 patients, Reuters has reported.
But more recently, the company was negotiating a lower number of patients with the agency after it raised safety concerns, current and former employees said.
It is not known how many patients the FDA ultimately approved.
Musk envisions brain implants could cure a range of conditions including obesity, autism, depression and schizophrenia as well as enabling Web browsing and telepathy.
He made headlines late last year when he said he was so confident in the devices' safety that he would be willing to implant them in his children.
On at least four occasions since 2019, Musk predicted Neuralink would begin human trials. But the company sought FDA approval only in early 2022, and the agency rejected the application, Reuters reported in March.
The FDA had pointed out several safety concerns to Neuralink that needed to be addressed before sanctioning human trials, Reuters reported.
Some of the issues involved the lithium battery of the device, the possibility of the implant's wires migrating within the brain, and the challenge of safely extracting the device without damaging brain tissue.