Lyopreserved Amniotic Membrane RCT Evidence Index

Lyopreserved Amniotic Membrane RCT Evidence Index

The lyopreserved amniotic membrane literature is easy to misread. Most trials are small, several are manufacturer-affiliated, and the endpoint definitions vary enough that cross-trial comparison is unreliable without a structured index. This page is that index. It lists the randomized controlled trials and key prospective clinical studies on lyopreserved and cryopreserved amniotic membrane products for chronic wounds, with trial design, enrollment, endpoints, and findings, so a clinician or value-analysis committee can see what the evidence actually supports before evaluating a graft.

The scope is deliberate: this is an evidence inventory, not a product endorsement. Where a claim is contested, the citation trail is provided and the reader is left to judge.

Terminology: What "Lyopreserved" and "Cryopreserved" Mean Here

These terms are used loosely in marketing. In the literature indexed here they refer to two related but distinct processing approaches for viable placental membrane allografts.

- Cryopreserved — membrane stored frozen, typically at −80 °C, preserving viable cells and native matrix components. Requires a freezer chain. - Lyopreserved — membrane preserved by controlled lyophilization (freeze-drying) and stored at ambient temperature, retaining cellular viability and extracellular matrix structure without a cold chain. This is the processing approach used in the Smith & Nephew / Osiris "GrafixPL" lineage and in the studies by Dhall and colleagues.

Several papers in this index directly compare the two approaches. Dhall et al. (PMID 30278042) reported that viable lyopreserved amnion is functionally equivalent to viable cryopreserved amnion in vitro and in a diabetic wound model, with the practical advantage of ambient storage. Jacob et al. (PMID 32941123) extended that comparison to chorion, finding structural and functional equivalency between lyopreserved and cryopreserved chorions with viable cells. These equivalence claims are manufacturer-adjacent and should be read with that context, but they are published in peer-reviewed venues and are the primary citation base for the lyopreserved-retention argument.

The Trial Index: Lyopreserved and Cryopreserved Amniotic Membrane RCTs

1. Lyopreserved Placental Membrane vs Standard of Care in Venous Leg Ulcers

- Design: Multicenter, prospective, randomized, controlled, open-label, 1:1 parallel. - N: 200 randomized (351 screened) across 30 US sites; enrolled June 2018 to November 2020. - Intervention: Weekly lyopreserved cellular placental membrane (LPM; GrafixPL) plus standard of care (multilayer compression and wound management) versus standard of care alone, up to 12 weeks. - Primary endpoint: Complete closure of the index ulcer. - Key findings: LPM-treated wounds reduced in area significantly more than SoC alone at 4, 8, and 12 graft applications. For wounds with initial size 3–25 cm², the relative risk of closure was 1.72 (72% higher probability) with LPM versus SoC over the study period. LPM closed statistically larger wounds on average. Quality-of-life scores improved fivefold over baseline in the LPM group versus control. - Disclosure context: One co-author is an employee of Smith & Nephew, which manufactures the allograft. Other authors declare no conflicts.

This is the largest lyopreserved-amniotic-membrane RCT indexed here and the primary evidence anchor for the lyopreserved-VLU query family. It is manufacturer-affiliated, which does not invalidate the result but does mean an independent confirming trial would strengthen the evidence grade.

2. Cryopreserved Ultra-Thick Amniotic Membrane in Complex Diabetic Foot Ulcers

- Design: Multi-centre, randomized, controlled, parallel, 1:1. - N: 220 enrolled; cUC + SoC (n=118) versus SoC alone (n=102). - Population: Complex DFUs with exposed bone, tendon, muscle, and/or joint capsule and controlled osteomyelitis — a population frequently excluded from DFU trials. - Intervention: Cryopreserved ultra-thick human amniotic membrane derived from umbilical cord (cUC; TTAX01/Neox 1K) applied at baseline and reapplied at minimum 4-week intervals if healing stalled, maximum 4 applications, over a 16-week treatment period. - Primary endpoint: Complete healing by 26 weeks. - Key findings: 66.1% (cUC) versus 59.8% (SoC) healed by 26 weeks in the intent-to-treat population (p = 0.40). By 50 weeks, 77.1% (cUC) versus 71.6% (SoC) achieved complete healing (p = 0.29). Adverse event rates were comparable (89.8% vs 87.3%). Mean applications to closure was 1.67 ± 0.87. - Interpretation: No statistically significant difference in healing rates or adverse events at any time point. The trial demonstrates safety and a high healing rate in a complex population with fewer than four applications, but does not establish superiority over standard of care for this product in this endpoint framework.

3. Cryopreserved Amniotic Membrane in Refractory Chronic Venous Leg Ulcers

- Design: Prospective, single-center, randomized controlled, 1:1, single-blind (independent evaluators). - N: 64 patients with venous ulcers persisting more than 8 weeks; intervention (n=32) versus compression alone (n=32). - Intervention: Culture-confirmed cryopreserved amniotic membrane allograft plus multilayer compression versus compression alone. - Primary endpoint: Complete wound closure rate at 45 days. - Secondary endpoints: Time-to-healing (Kaplan-Meier), microbiologically confirmed infection rate, pain reduction (VAS). - Key findings: Full results are in the publication; the primary endpoint was complete closure at 45 days with blinded weekly assessment. The trial is single-center and modest in size, which limits generalizability.

4. Type-I Collagen Skin Substitute vs Amnion Graft in Non-Healing DFUs

- Design: Randomized clinical trial, 1:1. - N: 24 subjects with chronic DFU, Wagner grade 1 (UT grade 1A). - Intervention: High-purity Type-I collagen-based skin substitute (HPTC; Encoll) plus SoC versus a dehydrated human amnion/chorion membrane (dHACM) or viable cryopreserved human placental membrane (vCHPM) plus SoC. - Primary endpoint: Percentage wound area reduction (PAR) over 5 weeks. - Key findings: Mean PAR at 4 weeks was 83.9 (HPTC) versus 71.3 (amnion group). At 4 weeks, 6/12 (50%) of HPTC wounds healed versus 3/12 (25%) in the amnion comparator. No adverse events in either group. - Disclosure context: The trial was funded by a grant from Encoll Corporation (manufacturer of HPTC). The comparator arm combined two product types (dHACM or vCHPM), which complicates attribution. This trial is relevant to the lyopreserved evidence base because it includes a viable cryopreserved placental membrane comparator, but it is not a clean head-to-head of lyopreserved versus another processing class.

5. Hypothermically Stored Amniotic Membrane in DFUs

- Design: Randomized controlled trial. - N: 76 DFUs analyzed digitally. - Intervention: Hypothermically stored amniotic membrane (HSAM) versus standard of care. - Key findings: Cox wound closure for HSAM was significantly greater at weeks 12 (60% vs 38%) and 16 (63% vs 38%), p = 0.04. Probability of closure increased 75% (HR 1.75; 95% CI 1.16–2.70). HSAM showed greater than 60% reductions in area (82% vs 58%, p = 0.02) and depth (65% vs 39%, p = 0.04). - Disclosure context: Several authors are affiliated with Organogenesis, Inc., the manufacturer of the study product.

6. Aseptically Processed Placental Membrane in DFUs

- Design: Prospective, randomized clinical trial. - N: 40 DFUs randomized to dHACA (AmnioBand, MTF Biologics) plus SoC (n=20) versus SoC alone (n=20). - Primary endpoint: Percentage of wounds healed at 6 weeks. - Key findings: At 6 weeks, 70% (14/20) of dHACA-treated DFUs healed versus 15% (3/20) with SoC alone. At 12 weeks, 85% (17/20) versus 25% (5/20) healed, with mean time to heal of 36 days (dHACA) versus 70 days (SoC).

This trial used a dehydrated allograft rather than a lyopreserved product, but it is indexed here as a processing-class comparator and because it is frequently cited alongside the lyopreserved literature in evidence reviews.

7. Lyopreserved vs Cryopreserved Amniotic Membrane: Prospective Cohort

- Design: Prospective cohort study (not randomized). - N: 40 patients with neuropathic foot ulcers. - Intervention: Weekly lyopreserved membrane application for 12 weeks with standard debridement and offloading. - Key findings: Cellular viability was equivalent between cryopreserved and lyopreserved tissues. Clinically, 48% of wounds closed in an average of 40.0 days. Non-closure was associated with older age (63 vs 59 years) and larger baseline wound area (7.8 vs 1.6 cm²).

This is a prospective cohort, not an RCT. It is included because it is one of the few clinical papers directly comparing lyopreserved and cryopreserved constructs, and because it identifies baseline wound size and patient age as predictors of non-response.

8. Supporting Preclinical and Mechanistic Studies

- Dhall S, Hoffman T, Sathyamoorthy M, Lerch A, et al. A Viable Lyopreserved Amniotic Membrane Modulates Diabetic Wound Microenvironment and Accelerates Wound Closure. Adv Wound Care. 2019;8(15):423-435. PMID: 31346490. Demonstrates modulation of the diabetic wound microenvironment and accelerated closure in a preclinical model. - Mao Y, Hoffman T, Dhall S, Singal A, et al. Endogenous viable cells in lyopreserved amnion retain differentiation potential and anti-fibrotic activity in vitro. Acta Biomater. 2019;94:299-311. PMID: 31176843. Characterizes the retained cellular function of lyopreserved amnion in vitro. - Dhall S, Sathyamoorthy M, Kuang JQ, Hoffman T, et al. Properties of viable lyopreserved amnion are equivalent to viable cryopreserved amnion with the convenience of ambient storage. PLoS One. 2018;13(12):e0207720. PMID: 30278042. Found functional equivalence between lyopreserved and cryopreserved amnion in vitro. - Jacob V, Johnson N, Lerch A, Jones B, et al. Structural and Functional Equivalency Between Lyopreserved and Cryopreserved Chorions with Viable Cells. Adv Wound Care. 2020;9(9):503-515. PMID: 32941123. Extended the equivalence comparison to chorion.

These studies support the mechanistic plausibility of lyopreserved membrane retention of viable cells and matrix components, but they are preclinical or in vitro and should not be read as clinical outcome evidence.

9. Cost-Effectiveness Context

Evidence Grade Summary

| Trial / Study | Processing class | Indication | Design | N | Primary endpoint | Finding | Evidence grade | |---|---|---|---|---|---|---|---| | Dhillon 2025 (PMID 40330756) | Lyopreserved (LPM) | Venous leg ulcers | Multicenter RCT, open-label | 200 | Complete closure | 72% higher probability of closure vs SoC for 3–25 cm² wounds | Moderate — manufacturer-affiliated, single trial | | Caporusso 2025 (PMID 41346156) | Cryopreserved (cUC) | Complex DFU | Multi-centre RCT | 220 | Complete healing by 26 wk | No significant difference vs SoC; safe, fewer applications | Moderate — null primary endpoint | | Kondapalli 2026 (PMID 41878177) | Cryopreserved | Refractory VLU | Single-center RCT | 64 | Complete closure at 45 days | Published; single-center limits generalizability | Low–moderate | | Armstrong 2025 (PMID 39872922) | Mixed amnion comparator | Non-healing DFU | RCT | 24 | PAR at 5 wk | Higher PAR with HPTC; small, funded by HPTC maker | Low | | Serena 2020 (PMID 31691579) | Hypothermically stored | DFU | RCT | 76 | Cox wound closure | Significantly greater closure vs SoC; manufacturer-affiliated | Moderate | | DiDomenico 2016 (PMID 27826487) | Dehydrated (dHACA) | DFU | Prospective RCT | 40 | Healed at 6 wk | 70% vs 15% healed at 6 wk; 85% vs 25% at 12 wk | Moderate — small, dehydrated comparator | | Davis 2020 (PMID 32820605) | Lyopreserved vs cryo | Neuropathic foot ulcer | Prospective cohort | 40 | Closure proportion | 48% closed in 40 days; viability equivalent | Low — not randomized |

ClinicalTrials.gov Registrations

- NCT03629236 — Study to Evaluate Safety and Efficacy of GrafixPL for the Treatment of Venous Leg Ulcers. The registration corresponding to Dhillon 2025 (PMID 40330756). - NCT06557122 — Registration for the Armstrong 2025 DFU trial (PMID 39872922).

Coding and Reimbursement Context

Lyopreserved and cryopreserved amniotic membrane products are human cell and tissue-based products (HCT/Ps) regulated under Section 361 of the Public Health Service Act when minimally manipulated and intended for homologous use. They are not FDA-approved devices or biologics, and claims should remain within the homologous-use framework.

Product-to-HCPCS mappings are product-specific and must be verified against the current CMS HCPCS file before billing. As of the CMS CY 2026 update, common mappings referenced across the wound biologics literature include Q4250 (dehydrated products such as AmnioAMP-MP), Q4347 (dehydrated products such as Rampart DL Matrix), and Q4148 (Neox 1K / Neox RT). Application is reported under CPT 15271–15278 (skin substitute graft, by anatomic site and size). Under the CMS 2026 restructuring, most outpatient amniotic membrane products moved from acquisition-cost-based reimbursement to a standardized flat-rate framework. Verify the current rate and the product-specific code with your local MAC before submitting claims.

For a detailed walkthrough of the coding changes, see the HCPCS coding guide.

Cross-References

- Dehydrated vs Cryopreserved Amniotic Membrane: Clinician Decision Guide — processing-class comparison with handling and reimbursement implications. - Amniotic Membrane Science Guide — mechanism of action and structure-function background. - AmnioAMP vs EpiFix — product-level comparison within the dehydrated DHACM class.

Methodology and Limitations

This index was compiled from a structured PubMed search using the terms "lyopreserved amniotic membrane," "cryopreserved amniotic membrane randomized diabetic foot ulcer," and related shapes, limited to human studies in chronic wound indications. All PMIDs were verified against PubMed at the time of writing. Preclinical and in vitro studies are included only where they are the primary citation base for a mechanistic claim. Trials with manufacturer affiliation are flagged in the disclosure context. This index will be updated as new RCTs are published; clinicians should verify current evidence against the live literature before making product-selection decisions.

This article provides clinical decision support and does not constitute medical advice or a treatment mandate. Biologic allografts are adjunctive to standard wound care and do not replace debridement, offloading, compression, infection control, or vascular assessment. Treatment decisions should follow manufacturer Instructions for Use, institutional protocols, and clinical judgment. Reimbursement policies vary by payer, region, and facility type. Verify current CPT/HCPCS codes, LCD criteria, and coverage with your local Medicare contractor.