WARNING LETTER
Estar Technologies Ltd
MARCS-CMS 716831 —
April 22, 2026
Delivery Method:
Via UPS and EMAIL
Reference #:
CBER 26-716831
Product:
Biologics
Medical Devices
Recipient:
Recipient Name
Aaron Esteron
Recipient Title
Chief Executive Officer and Founder
Estar Technologies Ltd
15, Ha-Merkava
Holon
5885111
Israel
Aaron@estar-medical.com
Issuing Office:
Center for Biologics Evaluation and Research
United States
WARNING LETTER
April 22, 2026
CBER 26-716831
Dear Mr. Esteron:
The United States Food and Drug Administration (FDA) has learned that your firm is offering for sale the Tropocells® PRP kit, Tropocells® PRF kit, Tropocells® TRS kit, Tropocells® PRFM kit, TropoVisc™ kit, Tropokine™ kit, and Cellenis® PRP kit (hereafter, “your devices”) in the United States without marketing clearance or approval, in violation of the Federal Food, Drug, and Cosmetic Act (the Act). Under section 201(h) of the Act, 21 U.S.C. § 321(h), your devices are intended for use in the diagnosis of disease or other conditions or in the cure, mitigation, treatment, or prevention of disease, or are intended to affect the structure or any function of the body.
Based on information and records reviewed by FDA, including your websites at https://www.tropocells.com and https://estar-medical.com/ (last visited April 2026), your devices are adulterated under section 501(f)(1)(B) of the Act, 21 U.S.C. § 351(f)(1)(B), because your firm does not have approved applications for premarket approval (PMA) in effect pursuant to section 515(a) of the Act, 21 U.S.C. § 360e(a), or approved applications for an investigational device exemption (IDE) under section 520(g) of the Act, 21 U.S.C. § 360j(g). Your introduction or delivery for introduction of your devices into interstate commerce, or the causing thereof is a prohibited act under section 301(a) of the Act, 21 U.S.C. § 331(a). Your devices are also misbranded under section 502(o) of the Act, 21 U.S.C. § 352(o), because your firm did not notify the agency of its intent to introduce your devices into commercial distribution, as required by section 510(k) of the Act, 21 U.S.C. § 360(k), and 21 CFR 807.81(a).
Of note, the TropoCells® PRP kit was cleared under premarket notification (510(k)) submission number BK110035 with the following indication, “safe and rapid preparation of autologous platelet-rich plasma (PRP) from a small sample of blood at the patient point of care. The PRP is mixed with autograft and/or allograft bone prior to application to a bony defect for improving handling characteristics.” However, you include statements such as the following on your website, https://www.tropocells.com, regarding the uses of the Tropocells® PRP kit:
“Tropocells® PRP is the ideal autologous technology for the healing of: musculoskeletal injuries, joint and osteoarthritis treatment, sports injuries, wound healing, ophthalmology, dentistry and oral surgery, and post-surgical recovery.”
These represent major changes or modifications to the intended uses for this device and are changes or modifications that could significantly affect its safety or effectiveness. Therefore, premarket notification for this device is required. See 21 CFR 807.81(a)(3).
For a device requiring premarket approval, the notification required by section 510(k) is deemed satisfied when a PMA is pending before the FDA. 21 C.F.R. § 807.81(b). The kind of information that you need to submit in order to obtain approval or clearance for your devices is described on the Internet at http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/HowtoMarketYourDevice/default.htm. FDA will evaluate the information that your firm submits and decide whether the products may be legally marketed.
Conclusion
Estar Technologies Ltd. should cease any activities that result in the misbranding or adulteration of the Tropocells® PRP kit, Tropocells® PRF kit, Tropocells® TRS kit, Tropocells® PRFM kit, TropoVisc™ kit, Tropokine™ kit, and Cellenis® PRP kit, such as the commercial distribution of the devices for the uses discussed above.
Your firm should take prompt action to address any violations identified in this letter. Failure to promptly adequately address this matter may result in regulatory action being initiated by the FDA without further notice. These actions include, but are not limited to, seizure, injunction, and civil money penalties.
Please notify our office in writing within fifteen business days from the date you receive this letter of the specific steps your firm has taken to address the noted violations, as well as an explanation of how your firm plans to prevent these violations, or similar violations, from occurring again. Include documentation of the corrections and/or corrective actionsyour firm has taken. If your firm’s planned corrections and/or corrective actions will occur over time, please include a timetable for implementation of those activities. If corrections and/or corrective actions cannot be completed within fifteen business days, state the reason for the delay and the time within which these activities will be completed. Your firm’s response should be comprehensive and address any violations included in this Warning Letter. If you believe that your devices are not in violation of the Act, include your reasoning and any supporting information for our consideration as part of your response.
Send your electronic response and any questions regarding this letter to CBER’s Office of Compliance and Biologics Quality, Division of Case Management at CBERDCMRecommendations@fda.hhs.gov.
Sincerely,
/S/
Melissa J. Mendoza
Director
Office of Compliance and Biologics Quality
Center for Biologics Evaluation and Research
Cc: Mr. Irving L. Wiesen, Esq
US Agent
Law Offices of Irving L. Wiesen PC.
420 Lexington Avenue, Suite 2400
New York, New York 10170
lwiesen@Wiesenlaw.com
Content current as of:
05/12/2026
Regulated Product(s)
Biologics
Medical Devices