Regenerative medicine · 3D bioprinting
Volumetric Biotechnologies
A Rice University spin-out that printed a hydrogel air sac able to oxygenate flowing blood, sold to 3D Systems in 2021 for a headline $400 million, and watched the entire contingent half of that number disappear within three years.
A lung that breathed on a lab bench
In a Rice University lab in 2019, a teardrop of clear hydrogel the size of a coin expanded and contracted in a steady rhythm. Air moved through an airway at its center, blood through a shroud of vessels around it. The two networks never touched. Oxygen crossed anyway, and red blood cells flowing past picked it up.
That object went on the cover of Science on May 3, 2019. It was not an organ. It was proof that the hardest structural problem in tissue engineering, two interpenetrating vessel networks inside one soft biocompatible block, could be solved with a cheap printer.
The trick was food dye. The team printed layer by layer from a liquid that hardens under blue light, adding dyes that absorb blue light so each layer set only where it should. The printer was released open source as SLATE.
The problem it was aimed at
More than 100,000 people sit on the United States transplant waiting list. Bioprinting answers both the shortage and the rejection problem at once, in principle: print the replacement from the patient’s own cells.
In practice the field kept hitting one wall. Cells packed densely enough to do an organ’s work die without a blood supply, and nobody could print the plumbing. “One of the biggest road blocks to generating functional tissue replacements has been our inability to print the complex vasculature that can supply nutrients to densely populated tissues,” Jordan Miller said when the paper came out. His collaborator Kelly Stevens of the University of Washington put the timescale plainly: “Tissue engineering has struggled with this for a generation.”
The same study printed constructs loaded with primary liver cells and implanted them in mice with chronic liver injury. The cells survived. That is the ceiling of what was shown: benchtop physics in a dish, and a cell survival result in rodents.
A professor and his graduate student
Miller took his biology degree at MIT in 2003 and his bioengineering PhD at Rice in 2008, then returned as faculty. Bagrat Grigoryan was his graduate student and lead co-author on the Science paper. They founded Volumetric in 2018 to sell the printers, bioinks and materials the lab had built.
Miller was an open source partisan: the data, the printer build files and the hydrogel designs all went public. The company went through Y Combinator in the winter 2020 batch, took money from the Methuselah Foundation and Methuselah Fund, and in December 2020 moved into a 20,000 square foot space at Houston’s East End Maker Hub. It never filed a Form D of its own.
Four hundred million dollars, announced
On October 27, 2021, 3D Systems said it was buying the company. The release described “a $45 million closing payment, with up to $355 million additional opportunity linked to the attainment of significant steps in the demonstration of human applications over the next several years.” Rice ran the story as “Rice professor, grad student strike $45 million deal for startup.”
Since 2017, 3D Systems had been working with United Therapeutics on printing scaffolds for human lungs. Volumetric brought the vascular printing chemistry. Miller was named chief scientist for regenerative medicine, Grigoryan vice president.
The audited number is smaller. 3D Systems recorded the deal at $40,173 thousand: $24,814 thousand in cash and 720,022 shares valued at $15,358 thousand. The $4.8 million gap between the press release and the ledger has never been explained in a filing.
Why the earnout was never purchase price
The $355 million was split across seven scientific milestones, each due before December 31, 2030 or December 31, 2035, and each payable only if named Volumetric people were still employed when it was hit. Under US accounting rules that condition makes the money compensation rather than consideration, so 3D Systems expensed it the way salary is expensed, and only once a milestone looked probable.
Only one ever did. Against a single $65 million milestone the company booked $1.3 million of expense in 2021 and $15.9 million in 2022. In 2023 it cut the research budget behind that milestone, concluded it would not be met, and reversed $17.3 million.
Then the structure came apart. On February 24, 2024, 3D Systems terminated four of the seven milestones, the kidney and liver ones, because its strategic partner had withdrawn funding. Maximum exposure fell to $175 million. On March 29 the sellers opened dispute resolution seeking the full $355 million. On April 29 the two key employees resigned, and 3D Systems told them the remaining $175 million could no longer be earned because the employment condition had failed. The sellers say they left for good reason, which under the merger agreement would preserve their rights; the company “vigorously denies this claim.” A $1.8 million settlement offer made in August 2024 was still unanswered at the 2025 annual report.
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| Science, May 2019 | Grigoryan and colleagues, “Multivascular networks and functional intravascular topologies within biocompatible hydrogels.” Cover article. A hydrogel alveolar model oxygenated red blood cells during pulsatile ventilation, and liver cell constructs implanted in injured mice kept their cells alive. Science lists 1,309 Crossref citations. | Public record |
| Priority challenge | An eLetter on the Science article page argues the food dye photoblocker was reported earlier: “this is not the first reported use of a biocompatible food dye as a photoblocker for creating transparent hydrogels using light-based 3D printing.” No correction is attached. | Contested |
| Deal value | Announced as $45 million at closing, up to $400 million total. Recorded by the buyer at $40,173 thousand, plus about $1,306 thousand of acquisition costs. | Claim differs |
| What the buyer valued | Final allocation: goodwill $37,492 thousand, 93 percent of the price. Identifiable intangibles totalled $1,500 thousand, being product technology $1,100 thousand and customer relationships $400 thousand. | Public record |
| Earnout outcome | One milestone accrued then fully reversed in 2023. Four terminated February 24, 2024. Both key employees resigned April 29, 2024 and the remaining $175.0 million was declared not earnable. Dispute opened March 29, 2024. Nothing paid. | Public record |
| Lung program status | United Therapeutics reports ULung as a “development-stage engineered lung alternative” whose scaffolds “demonstrate gas exchange in preclinical models.” No human trial reported, four years after its chief executive hoped for clearance in under five. | Public record |
| Regulatory and clinical | No FDA 510(k) or PMA record and no registered trial found for the company or its products as of September 22, 2026. | Not found |
Read plainly: the science is real, published, heavily cited, and it stops at rodents. The business record is an unusually complete public account of an acquisition that bought a research team rather than a product. Ninety-three percent of the price went to goodwill, the buyer’s own valuers put $1.1 million on the technology, and the headline number was never purchase price. It was a decade long employment contract, and it ended in year three.
What to watch
- Whether the sellers file suit. None had as of the 2025 annual report, and the buyer reports no estimate of liability.
- An investigational new drug filing for ULung, still a development stage program.
- Whether 3D Systems keeps funding regenerative medicine, having already dropped kidney and liver work.
- Where Miller and Grigoryan land next. SLATE is open source, so the core method did not leave with the company.
In their words
“One of the biggest road blocks to generating functional tissue replacements has been our inability to print the complex vasculature that can supply nutrients to densely populated tissues.”
Jordan Miller, co-founder, Rice University release, 2019 · Primary source
“Tissue engineering has struggled with this for a generation.”
Kelly Stevens, University of Washington, co-lead of the study, 2019 · Primary source
“3D bioprinted organ replacements are still 5-10 years away from a first-in-human safety study, and there are more than 100,000 people in need right now.”
Jordan Miller, 3DHEALS interview, 2020 · Interview
“No one is doing large animal studies with whole organ bioprinting yet, because that large yet intricate structure simply cannot be built just yet.”
Jordan Miller, 3DHEALS interview, 2020 · Interview
“Broadening our team’s ability to deliver on the promise of organ therapy is a win for patients and medical care around the world, as well as Volumetric shareholders who believed in our promise from early phase development.”
Bagrat Grigoryan, co-founder, quoted by InnovationMap, 2021 · Independent
“Last week, it was exciting to show the public our 3D-printed human lung scaffold, but we’re thrilled to share that our 3D-printed lung scaffolds are now demonstrating gas exchange in animal models.”
Martine Rothblatt, chief executive, United Therapeutics, 2022 · Partner release
Related companies
Sources
- Public recordGrigoryan et al., Multivascular networks and functional intravascular topologies within biocompatible hydrogels
- Public recordeLetter on credit to earlier work, Science article page
- Public record3D Systems Form 10-K, FY2021, acquisition note
- Public record3D Systems Form 10-K, FY2022, purchase price allocation
- Public record3D Systems Form 10-K, FY2023
- Public record3D Systems Form 10-K, FY2024
- Public record3D Systems Form 10-K, FY2025
- Public recordUnited Therapeutics Form 10-K, FY2025
- IndependentOrgan bioprinting gets a breath of fresh air
- IndependentRice professor, grad student strike $45 million deal for startup
- IndependentHouston bioprinting startup to be acquired for up to $400M
- InterviewEngineering Vasculatures: Interview with Dr. Jordan Miller
- IndependentUnited Therapeutics and 3D Systems shoot for lung scaffold trials
- Company3D Systems Announces Acquisition of Volumetric Biotechnologies
- PartnerUnited Therapeutics Provides an Update on Its Organ Printing Programs
- AdviserHaynes Boone Advises on Acquisition of Volumetric Biotechnologies
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
