Skye Biologics Holdings LLC
FDA issued a warning letter to Skye Biologics Holdings LLC (El Segundo, CA, United States) on Dec 16, 2024, citing 21 CFR 1271.10, 21 CFR 1271.15, 21 CFR 1271.3, 21 CFR 1271.2 and 8 more regulations. Subject: Deviations, CFR, Regulations for Human Cells, Tissues & Cellular Products (HCT, Ps).
From the letter: “your products are unapproved new drugs in violation of section 505(a) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. §355(a).”
At a glance
What a reviewer notes before reading: findings, citations, the response deadline and what the letter warns of.
- Violations
- 10 findings · 8 issue types
- Cited
- 21 CFR 1271.10, 21 CFR 1271.15, 21 CFR 1271.3, 21 CFR 1271.2, 21 CFR 211.100, 21 CFR 211.42, 21 CFR 211.113, 21 CFR 211.160, 21 CFR 211.165, 21 CFR 211.192, 21 CFR 211.188, 21 CFR 211.166
- Response due
- Fifteen (15) working days of receipt
- FDA asks for
- 2 actions
- Named as possible actions
- Seizure, injunction
- Issued by
- Center for Biologics Evaluation and Research
- Published status
- No close-out recorded
AI assisted findings
Model-assisted reading of each issue. Open one to see the FDA text it comes from, and check it against the full letter.
01Registration, listing & premarketProducts are unapproved new drugs and unlicensed biological products marketed without an approved BLA.
your products are unapproved new drugs in violation of section 505(a) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. §355(a). Your introduction or delivery for introduction of your product[s] into interstatecommerce, or the causing thereof, is prohibited under sections 301(d) of the FD&C Act,21 U.S.C. § 331(d). Your products are also unlicensed biological products in violation of section 351(a) of the Public Health Service Act (PHS Act), 42 U.S.C. § 262(a).
02Other · 21 CFR 1271.10(a)(1), 21 CFR 1271.3(f)(1)Products fail to meet minimal manipulation criterion because processing alters original relevant characteristics of umbilical cord.
your products fail to meet the minimal manipulation criterion set forth in 21 CFR 1271.10(a)(1) and defined for structural tissue in 21 CFR 1271.3(f)(1) because your processing alters the original relevant characteristics of the umbilical cord related to its utility for reconstruction, repair, or replacement. The processing of the umbilical cord from the form of a conduit into a flowable form, drastically alters the physical state of the HCT/P. The umbilical cord is more than minimally manipulated because such processing alters the original relevant characteristics of the HCT/P relating to its utility to serve as a conduit by effectively altering or eliminating its physical integrity and tubular form.
03Other · 21 CFR 1271.3(c)Products fail to meet homologous use criterion because they are not intended to perform same basic function as in donor.
your products fail to meet the criterion that the HCT/Ps be “intended for homologous use only,” which means that the “labeling, advertising, or other indications of the manufacturer’s objective intent” demonstrate that the HCT/P is intended solely to perform “the same basic function or functions in the recipient as in the donor.” 21 CFR 1271.3(c) and 1271.10(a)(2). Your products are not intended to perform the same basic function or functions of the HCT/P in the recipient as in the donor (e.g., serving as a conduit). Rather, your products are intended for, e.g., modulation of inflammation and promotion of remodeling of tissues; anti-inflammatory, anti-fibrotic, and anti-microbial purposes; and supplementing or filling a void, which are not basic functions of umbilical cord in the donor.
04Production & process controls · 21 CFR 211.100(a)Failure to establish adequate written procedures for production and process controls; manufacturing processes not validated.
Failure to establish adequate written procedures for production and process controls designed to assure that the drug products have the identity, strength, purity, and quality that they are purported or represented to possess. 21 CFR 211.100(a). Specifically, your firm has not validated the manufacturing processes for your products with respect to identity, strength, quality, and purity.
05Sterility & aseptic processing · 21 CFR 211.42(c)(10)(iv), 21 CFR 211.113(b)Inadequate environmental monitoring in aseptic processing area; no nonviable particulate or viable microbial monitoring in ISO 5 hoods, no personnel monitoring.
Failure to have an adequate system for monitoring environmental conditions in an aseptic processing area, 21 CFR 211.42(c)(10)(iv), as well as failure to establish and follow appropriate written procedures that are designed to prevent microbiological contamination of drug products purporting to be sterile. 21 CFR 211.113(b). Your written procedures for environmental monitoring of your firm’s aseptic processing areas (e.g., laminar flow hoods) are not sufficient to detect problems and ensure low bioburden levels prior to sterilization. For example, a. You do not perform nonviable particulate monitoring or viable microbial (b)(4) monitoring within your ISO 5 laminar flow hoods in association with all production shifts. You also do not conduct personnel monitoring of operators who perform processing of your products. Due to the higher risk of microbial contamination in this environment where open processing occurs, environmental monitoring inside the laminar flow hood should be conducted in association with each batch. b. Your ISO 5 laminar flow hoods, which are used for tissue cleaning, rinsing, and weighing, are located within an unclassified area. The area immediately adjacent to the critical processing areas should be controlled and monitored to minimize the level of potential contaminants in the final product.
06Laboratory controls & testingFailure to establish laboratory controls with appropriate specifications, standards, sampling plans, and test procedures.
Failure to establish laboratory controls that include scientifically sound and appropriate specifications, standards, sampling plans, and test procedures designed to assure the components, drug product containers, closures, in-process materials, labeling, and drug products conform to appropriate standards of identity, strength, quality and purity. 21 CFR211.160(b). For example, you have not established appropriate specifications to assure that your products conform to appropriate standards of identity, strength, quality, and purity.
07Laboratory controls & testing · 21 CFR 211.165(b)Failure to perform appropriate laboratory testing, including endotoxin testing, on each batch of drug product.
Failure to perform appropriate laboratory testing, as necessary, of each batch of drug product required to be free of objectionable microorganisms.21 CFR 211.165(b). Specifically, you failed to perform endotoxin testing on final product batches. Such laboratory testing is necessary as your products are purported to be sterile.
08Investigations & OOS · 21 CFR 211.192Failure to thoroughly investigate unexplained discrepancies or batch failures, including three environmental monitoring action-level excursions.
Failure to thoroughly investigate any unexplained discrepancy or the failure of a batch or any of its components to meet any of its specifications whether or not the batch has been already distributed. 21 CFR 211.192. For example, from January 2021 to August 2022, you failed to investigate three action-level excursions for environmental monitoring observed in the a septic processing area (e.g., laminar flow hoods).
09Records & data integrity · 21 CFR 211.188(b)Failure to prepare batch production and control records documenting each significant step, including weights, saline amounts, processing parameters, and equipment identification.
Failure to prepare batch production and control records that document each significant step in the manufacture, processing, packing, or holding of your umbilical cord blood products. 21 CFR 211.188(b). Specifically, your batch production records do not include documentation of the accomplishment of each significant step in the manufacture of your products or the person(s) performing each of those steps, for example: a. The weight of, for e.g., umbilical cord tissue used in processing. b. The amount of saline used to formulate the final product. c. Processing of tissue in the (b)(4) machine, including weight of tissue processed, machine operational parameters, run time, and the number of runs completed. d. Identification of equipment, such as laminar flow hoods, used in processing.
10Stability & expiry · 21 CFR 211.166(a)Failure to establish and follow a written stability testing program; assigned five-year expiration date without supporting data.
Failure to establish and follow a written testing program designed to assess the stability characteristics of drug products and to use the results of such stability testing to determine appropriate storage conditions and expiration dates. 21 CFR 211.166(a). Specifically, your firm has assigned a five-year expiration date for your products without supporting data regarding the stability characteristics of the products.
Additional FDA passages
5 extracted findingsSelected FDA passages, not the complete letter.
Failure to establish adequate written procedures for production and process controls designed to assure that the drug products have the identity, strength, purity, and quality that they are purported or represented to possess. 21 CFR 211.100(a).** Specifically, your firm has not validated the manufacturing processes for your products with respect to identity, strength, quality, and purity.
Failure to perform appropriate laboratory testing, as necessary, of each batch of drug product required to be free of objectionable microorganisms.21 CFR 211.165(b).** Specifically, you failed to perform endotoxin testing on final product batches. Such laboratory testing is necessary as your products are purported to be sterile.
Failure to thoroughly investigate any unexplained discrepancy or the failure of a batch or any of its components to meet any of its specifications whether or not the batch has been already distributed. 21 CFR 211.192.** For example, from January 2021 to August 2022, you failed to investigate three action-level excursions for environmental monitoring observed in the a septic processing area (e.g., laminar flow hoods).
Failure to prepare batch production and control records that document each significant step in the manufacture, processing, packing, or holding of your umbilical cord blood products. 21 CFR 211.188(b).** Specifically, your batch production records do not include documentation of the accomplishment of each significant step in the manufacture of your products or the person(s) performing each of those steps, for example:
Failure to establish and follow a written testing program designed to assess the stability characteristics of drug products and to use the results of such stability testing to determine appropriate storage conditions and expiration dates. 21 CFR 211.166(a).** Specifically, your firm has assigned a five-year expiration date for your products without supporting data regarding the stability characteristics of the products.
What FDA requested
- Explain the basis for your determination regarding whether BioRenew™, HRT® BioPower-A, HRT® BioPower-C, and HRT® NX products require FDA premarket review.
- If you believe these products meet all criteria in 21 CFR 1271.10(a) for regulation solely under section 361 of the PHS Act, 42 U.S.C. 264, and 21 CFR part 1271, please explain that determination.
FDA Warning Letter
48 paragraphs · 5 sectionsText as published on FDA.gov, retrieved Sep 8, 2026. Layout added for reading; the wording is FDA’s. View on FDA.gov (opens in a new tab)
1Introduction
3 paragraphs
The United States Food and Drug Administration (FDA) inspected your facility, located at 2255 Campus Dr, El Segundo, CA 90245, between November 29, 2022 and December 9, 2022. During the inspection, FDA documented that your company manufactures “placental connective tissue matrix allograft” products derived from umbilical cord, namely BioECM™ (collectively, “your products1”).
This letter is to advise you that your products are unapproved new drugs in violation of section 505(a) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. §355(a). Your introduction or delivery for introduction of your product[s] into interstatecommerce, or the causing thereof, is prohibited under sections 301(d) of the FD&C Act,21 U.S.C. § 331(d). Your products are also unlicensed biological products in violation of section 351(a) of the Public Health Service Act (PHS Act), 42 U.S.C. § 262(a).
This warning letter also summarizes significant violations of current good manufacturing practice (CGMP) requirements, including violations of section 501(a)(2)(B) of the FD&C Act, 21 U.S.C. § 351(a)(2)(B), and 21 CFR parts 210 and 211. Because your methods, facilities, or controls for manufacturing, processing, packing, or holding do not conform to CGMP, your drug products are adulterated within the meaning of section 501(a)(2)(B) of the FD&C Act, 21 U.S.C. § 351(a)(2)(B). Your introduction or delivery for introduction of your adulterated products into interstate commerce is a prohibited act under section 301(a) of the FD&C Act, 21 U.S.C. § 331(a).
2Unapproved New Drug and Unlicensed Biological Product Violations
9 paragraphs
Based on information and records reviewed by FDA prior to, during, and/or after the inspection, including information on your website, www.skyebiologics.com, your products are intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease or conditions in humans and/or are intended to affect the structure or function of the body. For example:
Your webpage for “Tissue Transplants Utilizing Extracellular Matrix Preservation (BioECM) Technology”, located at https://www.skyebiologics.com/technology, states that “Not all Placental Allografts are Created Equal… Placental tissues have been shown in the literature to be naturally anti-inflammatory, anti-fibrotic, anti-microbial, to modulate inflammation, promote tissue remodeling and reduce scar tissue formation in clinical applications.”
In a press release regarding your BioECM product, you state that “FastActing Amniotic Membranes are part of HRT’s & Skye’s extensive line of amniotic and placental products designed to help support proper tissue remodeling while modulating scarring and inflammation.”
Therefore, your products are drugs as defined in section 201(g)(1) of the FD&C Act, 21 U.S.C. § 321(g)(1), and biological products as defined in section 351(i) of the PHS Act, 42 U.S.C. § 262(i).
Your products are also human cells, tissues, or cellular or tissue-based products (HCT/Ps) as defined in 21 CFR 1271.3(d) and are subject to regulation under 21 CFR part 1271, issued under the authority of section 361 of the PHS Act, 42 U.S.C. § 264. HCT/Ps that do not meet all the criteria in 21 CFR 1271.10(a) are not regulated solely under section 361 of the PHS Act and the regulations in 21 CFR Part 1271. Unless an exception in 21 CFR 1271.15 applies, such products are regulated as drugs, devices, and/or biological products under the FD&C Act and/or the PHS Act and are subject to additional regulation, including, as applicable, premarket review. Based on a review of relevant materials, your company does not qualify for any exception in 21 CFR 1271.15, and your products fail to meet all criteria in 21 CFR 1271.10(a).
For example, your products fail to meet the minimal manipulation criterion set forth in 21 CFR 1271.10(a)(1) and defined for structural tissue in 21 CFR 1271.3(f)(1) because your processing alters the original relevant characteristics of the umbilical cord related to its utility for reconstruction, repair, or replacement. The processing of the umbilical cord from the form of a conduit into a flowable form, drastically alters the physical state of the HCT/P. The umbilical cord is more than minimally manipulated because such processing alters the original relevant characteristics of the HCT/P relating to its utility to serve as a conduit by effectively altering or eliminating its physical integrity and tubular form.
In addition, your products fail to meet the criterion that the HCT/Ps be “intended for homologous use only,” which means that the “labeling, advertising, or other indications of the manufacturer’s objective intent” demonstrate that the HCT/P is intended solely to perform “the same basic function or functions in the recipient as in the donor.” 21 CFR 1271.3(c) and 1271.10(a)(2). Your products are not intended to perform the same basic function or functions of the HCT/P in the recipient as in the donor (e.g., serving as a conduit). Rather, your products are intended for, e.g., modulation of inflammation and promotion of remodeling of tissues; anti-inflammatory, anti-fibrotic, and anti-microbial purposes; and supplementing or filling a void, which are not basic functions of umbilical cord in the donor.
Therefore, these HCT/Ps are not regulated solely under section 361 of the PHS Act, 42 U.S.C. § 264, and the regulations in 21 CFR part 1271.2 In addition to being regulated under section 361 of the PHS Act and 21 CFR part 1271, these products are regulated as drugs as defined in section 201(g)(1) of the FD&C Act, 21 U.S.C. § 321(g)(1), and biological products as defined in section 351(i) of the PHS Act, 42 U.S.C. § 262(i).
Subject to certain exceptions not applicable here, to lawfully introduce or deliver for introduction into interstate commerce a drug that is a biological product, a valid BLA must be in effect under section 351(a)(1) of the PHS Act, 42 U.S.C. § 262(a)(1). Such licenses are issued only after showing that the product is safe, pure, and potent. Your products are not the subject of an approved BLA.
3CGMP Violations
16 paragraphs
Additionally, during the inspection, FDA investigators documented evidence of significant violations from CGMP requirements, including violations from section 501(a)(2)(B) of the FD&C Act and 21 CFR parts 210 and 211.
At the close of the inspection, FDA investigators issued a Form FDA-483, List of Inspectional Observations, which described significant violations applicable to your products. FDA identified additional significant deviations upon further review of the information collected during the November 2022 inspection, as discussed below.
The CGMP violations include, but are not limited to, the following:
1. Failure to establish adequate written procedures for production and process controls designed to assure that the drug products have the identity, strength, purity, and quality that they are purported or represented to possess. 21 CFR 211.100(a). Specifically, your firm has not validated the manufacturing processes for your products with respect to identity, strength, quality, and purity.
2. Failure to have an adequate system for monitoring environmental conditions in an aseptic processing area, 21 CFR 211.42(c)(10)(iv), as well as failure to establish and follow appropriate written procedures that are designed to prevent microbiological contamination of drug products purporting to be sterile. 21 CFR 211.113(b). Your written procedures for environmental monitoring of your firm’s aseptic processing areas (e.g., laminar flow hoods) are not sufficient to detect problems and ensure low bioburden levels prior to sterilization. For example,
a. You do not perform nonviable particulate monitoring or viable microbial (b)(4) monitoring within your ISO 5 laminar flow hoods in association with all production shifts. You also do not conduct personnel monitoring of operators who perform processing of your products. Due to the higher risk of microbial contamination in this environment where open processing occurs, environmental monitoring inside the laminar flow hood should be conducted in association with each batch.
b. Your ISO 5 laminar flow hoods, which are used for tissue cleaning, rinsing, and weighing, are located within an unclassified area. The area immediately adjacent to the critical processing areas should be controlled and monitored to minimize the level of potential contaminants in the final product.
3. Failure to establish laboratory controls that include scientifically sound and appropriate specifications, standards, sampling plans, and test procedures designed to assure the components, drug product containers, closures, in-process materials, labeling, and drug products conform to appropriate standards of identity, strength, quality and purity. 21 CFR211.160(b). For example, you have not established appropriate specifications to assure that your products conform to appropriate standards of identity, strength, quality, and purity.
4. Failure to perform appropriate laboratory testing, as necessary, of each batch of drug product required to be free of objectionable microorganisms.21 CFR 211.165(b). Specifically, you failed to perform endotoxin testing on final product batches. Such laboratory testing is necessary as your products are purported to be sterile.
5. Failure to thoroughly investigate any unexplained discrepancy or the failure of a batch or any of its components to meet any of its specifications whether or not the batch has been already distributed. 21 CFR 211.192. For example, from January 2021 to August 2022, you failed to investigate three action-level excursions for environmental monitoring observed in the a septic processing area (e.g., laminar flow hoods).
6. Failure to prepare batch production and control records that document each significant step in the manufacture, processing, packing, or holding of your umbilical cord blood products. 21 CFR 211.188(b). Specifically, your batch production records do not include documentation of the accomplishment of each significant step in the manufacture of your products or the person(s) performing each of those steps, for example:
a. The weight of, for e.g., umbilical cord tissue used in processing.
b. The amount of saline used to formulate the final product.
c. Processing of tissue in the (b)(4) machine, including weight of tissue processed, machine operational parameters, run time, and the number of runs completed.
d. Identification of equipment, such as laminar flow hoods, used in processing.
7. Failure to establish and follow a written testing program designed to assess the stability characteristics of drug products and to use the results of such stability testing to determine appropriate storage conditions and expiration dates. 21 CFR 211.166(a). Specifically, your firm has assigned a five-year expiration date for your products without supporting data regarding the stability characteristics of the products.
4Response to the Form FDA-483
3 paragraphs
We acknowledge receipt of your letter received on January 3, 2023, which provides a response to FDA’s inspectional observations (FDA-483). We have reviewed the represented corrective actions outlined in the response, and these actions are not adequate to address the above-noted violations. For example, your response does not address your firm’s continued manufacture and distribution of your products or your plans for disposition of your current inventory manufactured under the violative conditions outlined above.
Your firm’s response repeatedly asserts that your products should be regulated solely under section 361 of the PHS Act, and that the violations noted above are not applicable to your products. Based on your position, you have not proposed corrective actions which address the CGMP violations noted above. While you assert that your products should be regulated solely under section 361 of the PHS Act, as explained above, the available evidence shows that your products do not meet all criteria in 21 CFR 1271.10(a) for regulation solely under section 361 of the PHS Act and the regulations in 21 CFR part 1271.
As such, your response further does not adequately address your lack of an approved BLA to lawfully market your products. As noted above, to lawfully market a drug that is a biological product, a valid biologics license must be in effect. 42 U.S.C. 262(a). Such licenses are issued only after showing that the product is safe, pure, and potent.
5Additional Concerns
5 paragraphs
In addition, we have concerns with your “placental connective tissue matrix allograft” products derived from umbilical cord, namely BioRenew™, and products derived from amniotic and chorionic membrane and umbilical cord, namely HRT® BioPower-A, HRT® BioPower-C, and HRT® NX. In your response, please explain the basis for your determination regarding whether these products require FDA premarket review. For example, if you believe these products meet all criteria in 21 CFR 1271.10(a) for regulation solely under section 361 of the PHS Act, 42 U.S.C. 264, and 21 CFR part 1271, please explain that determination.
Neither this letter nor the observations noted on the Form FDA-483, which were discussed with you at the conclusion of the inspection, are intended to be an all-inclusive list of deficiencies associated with your products. It is your responsibility to ensure that your establishment is in full compliance with the law.
This letter notifies you of our findings and provides you an opportunity to address them. Failure to adequately address these matters may lead to regulatory action without further notice. Such actions may include seizure and/or injunction.
We request that you respond in writing within fifteen (15) working days from your receipt of this letter, outlining the specific steps you have taken or plan to take to correct any violations, including an explanation of how you plan to prevent any violations, or similar violations, from occurring again. Include any documentation necessary to show that these matters have been addressed. If you cannot address these matters within fifteen (15) working days, please explain the reason for your delay and the timeframe for completion. If you do not believe your products are in violation of the FD&C Act, PHS Act, or applicable regulations, include your reasoning and any supporting information for our consideration.
Send your electronic response to CBERDCMRecommendations@fda.hhs.gov. If you have questions regarding this letter, contact the Division of Case Management, CBER at (240) 402-9156.
Citations and trends
Each 21 CFR section, ISO 13485 clause and issue type in this letter, how often it appears across all letters, and its trend by the year FDA issued the letters. 2026 runs to Nov 3, 2026, compared with the same dates last year. Select a row or a bar to see those letters in Letters. As cited in this historical letter, not a statement of current requirements.
Regulations
Also cited: 21 CFR 1271, 21 CFR 210
Issue types
Record details
- Issuing center
- Center for Biologics Evaluation and Research
- Issuing office
- Center for Biologics Evaluation and Research
- Location
- El Segundo, CA, United States
- Letter posted date
- May 20, 2025
- Letter issue date
- Dec 16, 2024
- Addressed to
- Chief Executive Officer
- Inspection dates
- Nov 29, 2022 to Dec 9, 2022
- Response window
- 15 working days after receipt of this letter
Read the source clause
We request that you respond in writing within fifteen (15) working days from your receipt of this letter, outlining the specific steps you have taken or plan to take to correct any violations, including an explanation of how you plan to prevent any violations, or similar violations, from occurring again.
- Record length
- 2,278 words · 2 recorded redactions
- Published status
- No published close-out
- FDA reference
- CBER-24-654466
- Original letter
- View on FDA.gov (opens in a new tab)
- Dataset last checked
- Nov 11, 2026 · How this is built
A response window is not a calculated due date. Source excerpts are selected passages. Finding interpretations and categories are model-assisted. Verify the original letter before relying on a finding.