Effect of amniotic membrane to reduce postlaminectomy epidural adhesion on a rat model

Amniotic Membrane Transplantation for Wound Healing, Tissue Regeneration and Immune Modulation

Amniotic membrane transplantation (AMT) has emerged as a versatile therapeutic modality with significant applications in wound healing, tissue regeneration, and ophthalmology. This review comprehensively evaluates AMT's efficacy in acute and chronic wound management, where it has been shown to alleviate pain, reduce infection risk, and facilitate epithelialization. In chronic wounds, AMT enhances healing through mechanisms such as re-epithelialization, angiogenesis, and immune modulation. Additionally, AMT exhibits promise in nerve regeneration, demonstrating potential in the repair of peripheral and central nervous system injuries by fostering neural recovery and minimizing scar formation. In ophthalmology, AMT is instrumental in corneal surface reconstruction, conjunctival repairs, and the management of dry eye syndrome and limbal stem cell deficiency. While the benefits of AMT are well-documented, this review also addresses significant challenges, including variability in success rates across different clinical conditions, ethical concerns regarding donor tissue usage, and regulatory hurdles impacting its broader clinical application. Furthermore, we integrate recent advances in the understanding of AMT's molecular mechanisms - such as its antioxidant effects via Nrf2/HO-1 pathway and immune modulation via P2X7 receptor pathways - and highlight innovative strategies including the incorporation of nanoceria nanoparticles, Vitamin D3 supplementation, and gene therapy approaches to enhance AMT outcomes. By exploring these dimensions, the review highlights not only the current state of AMT but also its potential future role in advancing regenerative medicine, including emerging applications in spinal cord repair, orthopaedics, and tissue engineering. This updated synthesis aims to inform clinicians and researchers about the multifaceted applications of AMT, promoting further investigation and optimization of this promising therapeutic approach.

Protective and Therapeutic Effects of Bovine Amniotic Fluids Collected in Different Trimesters on the Epidural Fibrosis After Experimental Laminectomy in Rats

BACKGROUND

The aim of this study was to investigate the protective and therapeutic effects of bovine amniotic fluid (BAF) on the inhibition of epidural fibrosis (EF) after experimental laminectomy.

METHODS

Forty female Sprague Dawley rats were used. The amniotic fluids were collected from each trimester of a pregnant cow. The rats were divided into 5 groups. Whereas no laminectomy was applied to the control group, animals in the sham group underwent laminectomy. Laminectomy was performed in the animals in other groups and the operation area was closed by dripping 1 mL of BAF collected in 3 trimesters of pregnancy. Animals were killed 28 days after the operation.

RESULTS

Compared with control, VEGF gene expression levels were downregulated approximately 5-fold in BAF-2. Whereas IL-6 was upregulated approximately 8-fold in the sham, it was downregulated 5-fold and 3-fold in BAF-1 and BAF-2, respectively. There was downregulation in BAF-2 and BAF-3 in terms of CD105 gene expression levels. TGFβ1 was upregulated approximately 2-fold in the sham group and downregulated in BAF-1 and BAF-2. Although histopathologic alterations including EF grade and fibroblast cell density were found to increase in the sham group, all BAF treatment decreased those of alterations. The highest CD105 immunoreactivity was detected in the sham group. All BAF treatment markedly aggravated fibrosis via decreasing CD105 immunoreactivity. In terms of grading parameters, almost the closest grades to the control were determined in the BAF-2. BAF collected in the second trimester is most effective in healing of scar tissue and preventing fibrosis via decreasing microvessel and fibroblast densities.

CONCLUSIONS

The results indicate that BAF may be used as a potential protective agent to prevent EF.

The Effect of Amniotic Tissue on Spinal Interventions: A Systematic Review

BACKGROUND

Amniotic membrane tissue has been thought to potentiate healing in many soft tissue conditions. Specifically, recent studies have shown its therapeutic potential for treatment in the setting of spinal pathologies. The purpose of this study is to thoroughly review the existing scientific literature and evidence concerning the clinical use of amniotic membrane-derived biologic agents on postoperative outcomes following spinal surgery.

METHODS

A systematic review was conducted following preferred reporting items for systematic reviews and meta-analyses guidelines using PubMed, Embase, and Cochrane databases up to December 2020 to identify animal and clinical studies examining the therapeutic potential for amniotic membrane tissue in the setting of spinal pathologies (including disc herniation, prevention of epidural fibrosis, and spinal fusion). Studies were broken down into 2 categories: experimental model type and the type of amnion product being analyzed.

RESULTS

A total of 12 studies (4 clinical studies and 8 studies utilizing animal models) met inclusion criteria. Additionally, the major types of amnion product were divided into cryopreserved/freeze-dried amniotic membrane, human amniotic fluid, human amniotic membrane, cross-linked amniotic membrane, and amnion-derived epithelial cells. While heterogeneity of study design precludes definitive specific results reporting, most studies showed positive benefits on healing/outcomes with amniotic augmentation. Specifically, amnion products have shown promising effects in reducing epidural adhesions and scar tissue after spine surgery, improving spinal fusion rate and postoperative pain scores, and promoting better functional outcomes after spine surgery.

CONCLUSIONS

A review of the limited number of reported studies revealed a wide variety of amniotic membrane preparations, treatment regimens, and indications, which limit definitive conclusions. To date, while there is no definitive clinical proof that amniotic tissues enhance tissue repair or regeneration, the aggregate results demonstrate promising basic science and outcomes potential in spinal surgery. Further study is warranted to determine whether this application is appropriate in the clinical setting.

CLINICAL RELEVANCE

This systematic review provides a summary of the existing literature regarding the use of amniotic membrane preparations, treatment regimens, and indications within spinal surgery. With the growing popularity and utilization of biologic agents such as amniotic membrane-derived products in orthopedic and neurologic surgery, this systematic review gives physicians a concise summary on the outcomes and indications associated with amniotic membrane products.

LEVEL OF EVIDENCE: 4

Biological properties and surgical applications of the human amniotic membrane

The amniotic membrane (AM) is the inner part of the placenta. It has been used therapeutically for the last century. The biological proprieties of AM include immunomodulatory, anti-scarring, anti-microbial, pro or anti-angiogenic (surface dependent), and tissue growth promotion. Because of these, AM is a functional tissue for the treatment of different pathologies. The AM is today part of the treatment for various conditions such as wounds, ulcers, burns, adhesions, and skin injury, among others, with surgical resolution. This review focuses on the current surgical areas, including gynecology, plastic surgery, gastrointestinal, traumatology, neurosurgery, and ophthalmology, among others, that use AM as a therapeutic option to increase the success rate of surgical procedures. Currently there are articles describing the mechanisms of action of AM, some therapeutic implications and the use in surgeries of specific surgical areas, this prevents knowing the therapeutic response of AM when used in surgeries of different organs or tissues. Therefore, we described the use of AM in various surgical specialties along with the mechanisms of action, helping to improve the understanding of the therapeutic targets and achieving an adequate perspective of the surgical utility of AM with a particular emphasis on regenerative medicine.

Human amniotic membrane as a dural substitute in neurosurgery: A systematic review

Background:

Several studies have highlighted the use of human amniotic membrane (HAM) in neurosurgical procedures as an effective dural substitute. HAM has inherent antifibrotic and anti-inflammatory properties and exhibits immunomodulatory effect that makes it an ideal dural substitute. Other advantages including easy availability, low cost of procurement, and storage also render it a promising dural substitute especially in low- and middle-income countries.

Methods:

A systematic literature search was performed using PubMed, Scopus, and Google Scholar databases, using the search terms “human amniotic membrane,” “dural repair,” and “neurosurgery.” To be eligible for inclusion in our review, papers had to report primary data, be published in English language and report dural repair on humans with human amniotic membrane. Eligibility assessment was conducted by two independent reviewers with qualitative analysis on the basis of surgical utility, postoperative complications, and histological analysis.

Results:

Eight articles met the predefined inclusion criteria, including three randomized control trials and five cohort studies. We evaluated the use of HAM grafts in dural repair for elective cranial surgery (four studies), trauma surgery (three studies), and elective spine surgery (one study). Cases with postoperative cerebrospinal fluid (CSF) leak were reported by two studies. Other postoperative complications including meningitis, hydrocephalus, pseudomeningocele, CSF collection in subdural space, and subacute subdural hematoma were reported by one study each. Postsurgical histological analysis was reported by three studies highlighting the antiadhesive and integrative properties of HAM.

Conclusion:

The current review of evidence suggests that in terms of postsurgical outcomes, HAM is comparable with commercially available dural substitutes.

Placental-based allograft use for tissue regeneration and scar prevention for neurosurgical wounds

Tweetable abstract Proper wound healing, including internal and surface tissue regeneration with the minimization of scar formation, is one of the most significant topics in surgical discussions and EpiFix^® dehydrated human amnion/chorion membrane allograft promotes healthy healing.

Reconstruction of Epidural Fat to Prevent Epidural Fibrosis After Laminectomy in Rabbits

Background: Laminectomy can effectively decompress the spinal cord and expand the vertebral canal. However, the fibrosis that appears may cause adherence and recompression of the spinal cord or/and nerve root, which may cause failed back syndrome (FBS) and make the reexposure process more difficult. Reconstruction of the epidural fat may be an ideal method to achieve satisfactory results. Methods: Thirty-six New Zealand rabbits were randomly divided into three groups: control, extracellular matrix (ECM), and ECM+aMSCs groups. Saline, ECM gel, and ECM+aMSC complex were placed, respectively, at the fifth lumbar vertebrate of the rabbits. Epidural fat and fibrosis formation were detected by magnetic resonance imaging (MRI) and histologically at the 4th, 8th, and 12th weeks. Quantitative RT-PCR was used to detect the expression of interleukin 6 (IL-6) and transforming growth factor β (TGF-β). Results: MRI and Oil Red O staining revealed epidural fat formation at the 12th week in the ECM+aMSCs group. Hematoxylin and eosin staining showed that the numbers of fibroblasts in the ECM gel and ECM+aMSCs groups were less than the control group at the 4th and 8th weeks (p < 0.05). Masson's trichrome staining showed that the proportion of collagen fibers in the ECM gel and ECM+aMSCs group was lower than the control group (p < 0.05). Quantitative RT-PCR showed the expressions of TGF-β and IL-6 were lower in the ECM gel and ECM+aMSCs group than those in the control group (p < 0.05) at the 4th week, but higher at the 8th week. Conclusion: We successfully reconstructed the epidural fat with ECM gel and aMSC complex; additionally, IL-6 and TGF-β cytokines were lower at early stage after laminectomy.

Effect of glutaraldehyde-crosslinked cartilage acellular matrix film on anti-adhesion and nerve regeneration in a rat sciatic nerve injury model

Decellularized extra-cellular matrix (ECM) has been studied as an alternative to anti-adhesive biomaterials and cartilage acellular matrix (CAM) has been shown to inhibit postoperative adhesion in several organs. This study aimed to evaluate the suitability of glutaraldehyde (GA) crosslinked CAM-films as anti-adhesion barriers for peripheral nerve injury. The films were successfully fabricated and showed improved physical properties such as mechanical strength, swelling ratio, and lengthened degradation period while maintaining the microstructure and chemical composition after GA crosslinking. In the in vitro study of CAM-film, the dsDNA content met the recommended limit of decellularization and more than 70% of the major ECM components were preserved after decellularization. The adhesion and proliferation of seeded human umbilical vein endothelial cells and fibroblasts were significantly lower in CAM-film than in control, but similar with Seprafilm. However, the CAM-film extract did not show cytotoxicity. In the in vivo study, the peri-neural fibrosis was thicker, adhesion score higher, and peri-neural collagen fibers more abundant in the control group than in the CAM-film group. The total number of myelinated axons was significantly higher in the CAM-film group than in the control group. The inflammatory marker decreased with time in the CAM-film group compared to that in the control group, whereas the nerve regenerative marker expression was maintained. Moreover, the ankle angles at contracture and toe-off were higher in the CAM film-treated rats than in the control rats. GA-crosslinked CAM films may be used during peripheral nerve surgery to prevent peri-neural adhesion and enhance nerve functional recovery.

Homologous amniotic membrane as a dural substitute in decompressive craniectomies

INTRODUCTION

A dura mater substitute in decompressive craniectomies must protect the brain while providing a dissection plane between the cortex and myocutaneous layer. The human amniotic membrane (AM) has anti-inflammatory, wound healing, and differentiation properties. We tested AM properties as a dural substitute by comparing the outcomes to biological ones.

METHODS

We prospectively collected data on 25 patients who randomly underwent decompressive craniectomy with lyophilized AM patches and 25 in which biological substitutes were utilized between 2015 and 2019. The AM was laid with the epithelial side facing the brain because of the anti-adhesive proprieties, while the chorion facing the myocutaneous flap. We collected data on demographics, neurological status, comorbidities, and surgical outcomes. Additionally, we created a score - dura mimicking score- and reviewed postoperative imaging and pathological specimens.

RESULTS

The majority (96%) of AM grafts were integrated into native dura. Thirteen patients scored as excellent and 11 good on our "dura mimicking score", showing tissue integration ability but no cerebral cortex adhesion. The histopathological analysis showed that AM had thick plates of dense fibrous tissue with small reactive vessels, reactive fibroblasts, and lymphocytes infiltrate. The AM group's first outcomes were not different from the biological substitute patients but higher integration rate to the dura and less adhesion to the myocutaneous flap in AM patients.

CONCLUSIONS

We documented the anti-adhesive, protective, and integrative properties of AM dural substitute patches in patients who underwent decompressive craniectomies, comparing the intraoperative differences and postoperative outcomes to biological dural substitutes.

Treating Public Health Dilemma of Gingival Recession by the Dehydrated Amnion Allograft: A 5-Year Longitudinal Study

Aim: This study aimed to evaluate the efficacy of dehydrated amnion allograft with coronally positioned flap procedure in paired Miller's class I recession defects.

Methods: A total of 51 subjects were included in the study with bilateral Miller's class I gingival recession defects. In the test group, patients were treated with an amniotic membrane (AM) with a coronally positioned flap, while in the control group, patients were treated with coronally positioned flap alone. Clinical parameters such as recession depth, recession width (RW), probing depth (PD), relative attachment level (RAL), width of keratinized gingiva (WKG), and thickness of keratinized gingiva (TKG) were recorded at baseline and after 5 years of follow-up.

Result: The mean baseline recession was 2.95 ± 0.89 in the test group and 2.70 ± 0.85 in the control group, and both were statically non-significant. At the end of 6 months, all the parameters, when compared with the baseline, showed a significant improvement. Intergroup comparison showed the non-significant difference in all settings except the TKG.

Conclusion: AM proved to help improve the TKG. This increase in thickness helps in the long-term maintenance of the gingival margin in Miller's class I recession defect.

Orthobiologic Supplementation Improves Clinical Outcomes Following Lumbar Decompression Surgery

Background

Endoscopic-assisted lumbar decompression is a minimally invasive spine surgery which has been touted to reduce collateral tissue damage, incisional pain, recovery time and complications. Residual back or leg pain and recurrent herniation are commonly reported post-operative outcomes. It has been suggested that injecting orthobiologics like cryopreserved amniotic-derived products (ADPs) and bone marrow aspiration (BMA) into the surgery site would have additional benefit on patient outcomes. This is a Western Institutional Review Board (WIRB)-approved level 1, randomized controlled trial of prospectively collected patient demographic and outcomes data for endoscopic-assisted lumbar decompression surgery. The primary goal of this study was to compare patient outcomes of orthobiologic supplementation during endoscopic-assisted lumbar decompression surgery.

Methods

Following WIRB approval, 269 patients underwent lumbar endoscopic-assisted decompressive surgery between January 2011 and October 2017. Patients were randomized to receive ADP, BMA, both, or no supplementation (control group). Outcomes were measured by post-operative questionnaires (visual analog scale (VAS), Oswestry disability index (ODI), 36-item short-form health survey (SF-36)) over 12 months.

Results

Mean VAS-leg for either BMA or ADP group displayed statistically significant improvements at 2 weeks (3.55 vs. 4.77, P = 0.002), 6 months (2.34 vs. 3.37, P = 0.026), and 9 months (2.18 vs. 3.57, P = 0.01) compared to no supplementation group (control group). Similarly, improvements in mean VAS-back were significant at 2 weeks (3.98 vs. 5.01, P = 0.011), 2 months (3.22 vs. 3.93, P = 0.04), 9 months (2.38 vs. 4.11, P = 0.004), and 12 months (2.23 vs. 3.58, P = 0.011) compared to no supplementation group (control group). There were statistically significant differences in the ODI (2 weeks, 42.19 vs. 31.11, P = 0.014) and SF-36 (4 months, 85 vs. 63, P = 0.043 for ADP only), but these differences did not subsist over time. Two patients (one control, one ADP) re-herniated at the same level.

Conclusions

Orthobiologic BMA and ADP resulted in improved pain control during early post-operative periods.

Human Amniotic Membrane for the Prevention of Intradural Spinal Cord Adhesions: Retrospective Review of its Novel Use in a Case Series of 14 Patients

BACKGROUND

Tethering after spinal surgery is caused by adhesions that arise from intradural tissue manipulation. Microsurgical detethering is the only treatment for symptomatic patients, but retethering occurs commonly and no treatment is widely available to prevent this complication.

OBJECTIVE

To apply human amniotic membrane (HAM) grafts, which are immune-privileged and known to possess antifibrogenic properties, in patients requiring microsurgical detethering. For this first-in-human use, we evaluated the safety and potential efficacy of these grafts for preventing retethering.

METHODS

We retrospectively reviewed the medical records of all patients who required detethering surgery and received an HAM graft between 2013 and 2016 at our institution after various previous intradural spinal surgeries. In all 14 cases, intradural lysis of adhesions was achieved, an HAM graft was sewn in place intradurally, and a dural patch was closed in a watertight fashion over the graft.

RESULTS

Fourteen patients had received HAM grafts to prevent retethering. All patients had at least 6 mo of follow-up (mean follow-up, 14 mo). Retethering was noted in only 1 patient. Surgical re-exploration showed that the retethering occurred caudal to the edge of the HAM graft, with no tethering underneath the original graft. No complications were attributed specifically to the HAM graft placement.

CONCLUSION

This first-in-human series provides evidence that HAM grafts are a safe and potentially efficacious method for preventing retethering after microsurgical intradural lysis of adhesions. These results lay the groundwork for further prospective controlled trials in patients with this difficult-to-treat pathology.

Effect of topical rifamycin application on epidural fibrosis in rats

Objectives

This study aims to investigate the effects of topical rifamycin SV application on epidural fibrosis formation in a rat model.

Materials and methods

Between March 2015 and April 2015, a total of 20 Wistar rats were equally and randomly divided into laminectomy only group (control group) and laminectomy and rifamycin SV group (treatment group). Laminectomy was performed between L3-L5 in all rats. Surgical field was irrigated with 1 mL rifamycin SV (1 mL). After four weeks, vertebral columns of the rats were removed en bloc between the L1 and L5 levels, and epidural fibrosis and arachnoid involvement were histopathologically evaluated and graded.

Results

Grade 3 epidural fibrosis formation ratio was lower in the treatment group (40%) compared to the control group (80%). However, there was no statistically significant difference between the treatment and control groups in terms of epidural fibrosis (p=0.164) and arachnoid involvement (p=0.303).

Conclusion

Intraoperative rifamycin irrigation tends to reduce epidural fibrosis formation risk, although not statistically significant.

An investigational study of a dual-layer, chorion-free amnion patch as a protective barrier following lumbar laminectomy in a sheep model

The inherent properties of the human amniotic membrane (HAM) suggest its potential for use as a physical barrier during surgery to protect neural elements and vessels from the surrounding environment. The objective of this study was to evaluate the effect of a dual-layer, chorion-free amnion patch (DLAM; ViaShield®, Globus Medical Inc., Audubon, PA, USA) processed from HAM as a protective barrier following lumbar laminectomy in a sheep model. A multiplex immunoassay was performed to quantify the inherent cytokines present in the amnion after processing. Twelve skeletally mature female crossbred Suffolk sheep were randomly divided into two equal post-operative periods (4 and 10 weeks). Each sheep underwent a laminectomy at L3 and L5, and one of the surgical sites randomly received the DLAM treatment. At each postsurgical time point, the extent of epidural fibrosis and neurohistopathological responses at the laminectomy sites was assessed based on epidural fibrosis-dura tenacity scores and decalcified histology, respectively. Immunoassay results showed that inflammatory mediators and immunomodulatory cytokines were present in the amnion after processing, but no proangiogenic cytokines were detected. At 10 weeks, tissue tenacity was significantly less in the DLAM treatment group when compared with the operative control (1.2 ± 0.4 vs. 2.8 ± 0.4, p < 0.05), demonstrating the ability of DLAM to act as a barrier and cover the dura. Gross observations showed fewer fibroblasts in the DLAM group in comparison with the control at both post-operative time points. Fibroblast infiltration analysis indicated that at both 4 and 10 weeks, there were significantly more infiltrated fibroblasts in the operative control sites than in the DLAM-treated sites, expressed as a percentage of the total number of fibroblasts present (4 weeks: 72.3 ± 10.2% vs. 10.8 ± 10.1%, p < .05; 10 weeks: 84.9 ± 15.8% vs. 43.1 ± 11.6%, p < .05). Additionally, fibroblasts travelled further into the dura in the operative control group compared with the DLAM-treated group at both time points. In conclusion, this study found that DLAM reduced fibroblast infiltration and tissue tenacity following lumbar laminectomy in a sheep animal model. These findings support the potential use of DLAM in clinical practice as a protective barrier for neural elements and anterior vessels.

Prospective application of stem cells to prevent post-operative skeletal fibrosis

Post-operative skeletal fibrosis is considered one of the major complications causing dysfunction of the skeletal system and compromising the outcomes of clinical treatment. Limited success has been achieved using current therapies; more effective therapies to reduce post-operative skeletal fibrosis are needed. Stem cells possess the ability to repair and regenerate damaged tissue. Numerous studies show that stem cells serve as a promising therapeutic approach for fibrotic diseases in tissues other than the skeletal system by inhibiting the inflammatory response and secreting favorable cytokines through activating specific signaling pathways, acting as so-called medicinal signaling cells. In this review, current therapies are summarized for post-operative skeletal fibrosis. Given that stem cells are used as a promising therapeutic approach for fibrotic diseases, little effort has been undertaken to use stem cells to prevent post-operative skeletal fibrosis. This review aims at providing useful information for the potential application of stem cells in preventing post-operative skeletal fibrosis in the near future. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1236-1245, 2019.

Effects of Cryopreserved Amniotic Membrane-Umbilical Cord Allograft on Total Ankle Arthroplasty Wound Healing

Relatively high rates of wound healing complications continue to be reported with a total ankle arthroplasty (TAA) anterior incision. The amniotic membrane-umbilical cord (AM-UC) allograft is a regenerative orthobiologic adjunct that modulates wound healing by down-regulating inflammation, enhancing local healing and antimicrobial factors, and reducing scar formation. The purpose of this study was to determine whether local application of a cryopreserved AM-UC allograft enhances soft tissue healing after TAA. A total of 104 patients with symptomatic ankle arthritis who failed conservative management underwent standard TAA. At skin closure, patients were allocated to either the treatment (local application of AM-UC) or control (no allograft) group. Demographic data, patient comorbidities, and radiographic findings were collected. The primary outcome was a major complication necessitating reoperation. Secondary outcomes were time to healing, minor complications (i.e., skin dehiscence, local wound care, use of antibiotics), and patient scar assessment. Local application of an AM-UC allograft significantly decreased the overall time to skin healing (28.5 days vs 40 days; p = .03). Two patients required a reoperation for soft tissue wound complications, with no difference (p = 1.00) between the groups. No statistically significant difference was detected in terms of skin dehiscence, local wound care, or antibiotic prescriptions in the 2 groups. Regenerative technology using local application of a cryopreserved AM-UC allograft may enhance TAA outcomes by decreasing the time to healing. Larger randomized controlled trials are needed to determine whether an AM-UC allograft enhances soft tissue wound healing and ultimately reduces the incidence of devastating soft tissue complications.

Effects of silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model

The authors investigated the effects of a silk solution against laminectomy-induced dural adhesion formation and inflammation in a rat model. They found that it significantly reduced postlaminectomy dural adhesion formation and inflammation. Dural adhesion formation, thought to be an inevitable consequence of laminectomy, is one of the most common complications following spinal surgery, and the authors' results indicate that the silk solution might be a potential novel therapeutic agent for dural adhesion formation.

The Science and Clinical Applications of Placental Tissues in Spine Surgery

STUDY DESIGN

Narrative literature review.

OBJECTIVES

Placental tissue, amniotic/chorionic membrane, and umbilical cord have seen a recent expansion in their clinical application in various fields of surgery. It is important for practicing surgeons to know the underlying science, especially as it relates to spine surgery, to understand the rationale and clinical indication, if any, for their usage.

METHODS

A literature search was performed using PubMed and MEDLINE databases to identify studies reporting the application of placental tissues as it relates to the practicing spine surgeon. Four areas of interest were identified and a comprehensive review was performed of available literature.

RESULTS

Clinical application of placental tissue holds promise with regard to treatment of intervertebral disc pathology, preventing epidural fibrosis, spinal dysraphism closure, and spinal cord injury; however, there is an overall paucity of high-quality evidence. As such, evidence-based guidelines for its clinical application are currently unavailable.

CONCLUSIONS

There is no high-level clinical evidence to support the application of placental tissue for spinal surgery, although it does hold promise for several areas of interest for the practicing spine surgeon. High-quality research is needed to define the clinical effectiveness and indications of placental tissue as it relates to spine surgery.

Biochemical characterization of pure dehydrated binate amniotic membrane: role of cytokines in the spotlight

AIM

Placental allografts used for tissue regeneration differ in membrane compositions and processing techniques. A uniquely folded dehydrated binate amniotic membrane (DBAM) was biochemically characterized to evaluate its potential role in wound healing.

METHODS

Histology, Luminex-based immunoassay and standard in vitro cell biology techniques were employed.

RESULTS

Histological staining confirmed that the DBAM was chorion free with epithelial cell layer of the respective amnion membranes facing outward. DBAM had quantifiable levels of relevant cytokines that induced proliferation and migration while bolstering secretory activity of the cells. DBAM retained biological efficacy at a broad range of temperatures.

CONCLUSION

Cytokines in DBAM stimulate bone marrow stromal and stem cells that may lead to tissue regeneration and wound healing in a clinical setup.

Human-Derived Amniotic Membrane Is Associated With Decreased Postoperative Intraperitoneal Adhesions in a Rat Model

BACKGROUND

Complications from adhesions after intra-abdominal surgery accounts for ~6% of hospital admissions. Currently, hyaluronate/carboxymethylcellulose represents the main option to prevent postoperative adhesion formation. Human amniotic membrane contains inherent anti-inflammatory properties that mitigate adhesion formation.

OBJECTIVE

This study aimed to evaluate adhesion generation after surgical trauma with amniotic membranes compared with standard intraperitoneal adhesion barriers.

DESIGN

This study is a double-blinded, prospective evaluation.

SETTING

This study was conducted at an animal research facility.

ANIMALS

Forty male rats were studied.

INTERVENTION

Laparotomy was performed with peritoneal disruption to the cecum. Animals were randomly assigned to 1 of 5 groups: sham, control, saline, hyaluronic acid membrane, or amniotic membrane. Animals were euthanized at 14 days.

MAIN OUTCOME MEASURES

Independent gross and histological assessments of adhesions were analyzed between groups by using adhesion scoring and microscopy. Scoring was based on the percentage of the cecum involved (0-4), vascularity of adhesions (0-3), strength (0-3), inflammation (0-3), and fibrosis (0-3). Adhered tissue was harvested for polymerase chain reaction analysis for gene regulation activity.

RESULTS

All rats survived 14 days. Adhesions were observed in all animals. There were significantly fewer adhesions in the amniotic membrane group (2) versus hyaluronic acid (3) group (p = 0.01). The percentage of adhesion to the cecum was lower in the amniotic membrane group (29%) than in the hyaluronic acid group (47%, p = 0.04). Histological examination showed no significant difference between or within the 3 groups for inflammation or fibrosis. Genetic analysis of adhered tissues supported high rates of epithelialization and inhibition of fibrosis in the amniotic membrane group.

LIMITATIONS

We are limited by the small sample size and the preclinical nature of the study.

CONCLUSION

Human-derived amniotic membrane is effective at reducing intraperitoneal adhesion after surgical trauma and is superior to the current antiadhesion barriers. Amniotic membranes are well absorbed and demonstrate short-term safety. See Video Abstract at http://links.lww.com/DCR/A554.

Update on biomaterials for prevention of epidural adhesion after lumbar laminectomy

Lumbar laminectomy often results in failed back surgery syndrome. Most scholars support the three-dimensional theory of adhesion: Fibrosis surrounding the epidural tissues is based on the injured sacrospinalis behind, fibrous rings and posterior longitudinal ligaments. Approaches including using the minimally invasive technique, drugs, biomaterial and nonbiomaterial barriers to prevent the postoperative epidural adhesion were intensively investigated. Nevertheless, the results are far from satisfactory. Our review is based on various implant biomaterials that are used in clinical applications or are under study. We show the advantages and disadvantages of each method. The summary will help us to figure out ideas towards new techniques. The translational potential of this article: This review summarises recent biomaterials-related clinical and basic research that focuses on prevention of epidural adhesion after lumbar laminectomy. We also propose a novel possible translational method where a soft scaffold acts as a physical barrier in the early stage, engineered adipose tissue acts as a biobarrier in the later stage in the application of biomaterials and adipose-derived mesenchymal stem cells are used for prevention of epidural adhesion.

Upregulation of P27Kip1 by mitomycin C induces fibroblast apoptosis and reduces epidural fibrosis

Fibroblast excessive proliferation is considered as one of the major reasons of epidural fibrosis after laminectomy. Recent studies have shown that mitomycin C (MMC) could successfully reduce the formation of epidural fibrosis by inducing fibroblasts apoptosis. However, the detailed mechanism was still unclear. Increasing evidence indicated that P27^Kip1 (P27) could result in apoptotic cell death in various cells. In this study, we investigated whether MMC could induce fibroblasts apoptosis and reduce epidural fibrosis by regulating P27. Western blot analysis, Hoechst staining, Flow cytometry, and Cell Counting Kit-8 (CCK-8) assay were used to detect the effect of MMC on fibroblasts apoptosis by regulating P27 expression in vitro. Moreover, histological and immunohistochemical assays were used to evaluate the effect of MMC on reducing epidural fibrosis by regulating P27 expression in rats. The results showed that MMC could induce fibroblasts apoptosis and upregulate P27 expression in vitro. Knockdown of P27 partially attenuated MMC-induced expressions of P27 and cleaved PARP as well as increased the cell viability. MMC could reduce epidural fibrosis in a dose-dependent manner in rats by histological analysis. The expression of P27 was increased by MMC treatment as shown by immuohistochemical analysis. In conclusion, this study demonstrated that MMC could upregulate P27 expression, which subsequently induced fibroblasts apoptosis and reduced epidural fibrosis.

Cryopreserved Amniotic Membrane Improves Clinical Outcomes Following Microdiscectomy

STUDY DESIGN

Prospective, randomized controlled trial.

OBJECTIVE

To compare pain, physical/mental functional recovery and recurrent herniation for patients following lumbar microdiscectomy with and without the use of a cryopreserved amniotic tissue graft.

SUMMARY OF BACKGROUND DATA

Although microdiscectomy procedures are routinely successful for patients with lumbar radiculopathy due to herniated disc disease, residual low back pain, and recurrent herniation remain unsolved clinical problems.

METHODS

Following Investigated Review Board approval, 80 subjects were randomized in a 1:1 ratio to either receive cryopreserved amniotic (cAM) tissue or no tissue following elective lumbar microdiscectomy surgery. cAM grafts were applied to the annular defect at the conclusion of the procedure. Patients provided preoperative and postoperative clinical assessment data out to 24 months using the Oswestry Disability Index (ODI), Short Form-12 (SF-12) Health Survey, and Visual Analog Pain Scale for back and leg pain. Patients with symptomatic recurrent disc herniation were recorded.

RESULTS

In total, 48 males and 32 females with an average age of 47.2 years were included. Mean ODI scores for subjects treated with cAM graft demonstrated statistically greater improvement at 6 weeks (14.49 vs. 21.82; P=0.05) and 24 months (6.62 vs. 14.40; P=0.02) compared with controls. Similarly, SF-12 Physical Component Scores demonstrated statistically greater gains in the cAM group at both the 6 weeks and 24 months. None of the subjects in the cAM graft group sustained a recurrent herniation at the same surgical level, whereas 3 patients in the control group sustained a recurrent herniation at the same surgical level, with 2 requiring fusion to manage persistent pain.

CONCLUSIONS

The data demonstrate statistically superior clinical outcomes following lumbar microdiscectomy as measured by ODI and SF-12 (physical composite scale) and a lower rate of recurrent herniation with the use of a cAM tissue graft compared with traditional microdiscectomy.

Effects of Systemic and Local Interferon Beta-1a on Epidural Fibrosis

Study Design

Level 1 randomized controlled study.

Purpose

To investigate the effects of systemic and local interferon-beta-1a (IFN-β-1a) on prevention of epidural fibrosis using histopathological parameters.

Overview of Literature

Epidural fibrosis involves fibroblastic invasion of nerve roots into the epidural space. Formation of dense fibrous tissue causes lumbar and radicular pain. Many surgical techniques and several materials have been proposed in the literature, but no study has assessed the effect of IFN-β-1a on prevention of epidural fibrosis.

Methods

Forty-eight adult female Sprague-Dawley rats were divided into six groups of eight: sham group, control group, systemic 44 μg IFN-β-1a group and 22 μg IFN-β-1a group (after laminectomy and discectomy, 0.28 mL and 0.14 mL IFN-β-1a applied subcutaneously three times for a week, respectively), local 44 μg IFN-β-1a group (laminectomy and discectomy, followed by 0.28 mL IFN-β-1a on the surgical area), and local 22 μg IFN-β-1a group (laminectomy and discectomy, followed by 0.14 mL IFN-β-1a on the surgical area). All rats were sacrificed after 4 weeks and groups were evaluated histopathologically.

Results

Compared with sham and control groups, significantly less epidural fibrosis, dural adhesion, and fibroblast cell density were observed in the local and systemic 44 μg IFN-β-1a groups. No other differences were evident between the local and systemic groups.

Conclusions

IFN-β-1a is effective in preventing epidural fibrosis with systemic and local application.

Effects of hemostatic polysaccharide agent on epidural fibrosis formation after lumbar laminectomy in rats

BACKGROUND CONTEXT

Epidural fibrosis is a common adverse outcome of spinal surgery that can compress the dural sac and nerve root. Local hemostatic agents have many indications in numerous types of spinal surgery. As these agents may behave as foreign bodies, inducing inflammation and delaying regeneration, they could enhance the risk of epidural fibrosis.

PURPOSE

We evaluated the effects of hemostatic polysaccharide on epidural fibrosis development in laminectomized rats.

STUDY DESIGN

This is a randomized controlled trial.

OUTCOME MEASURES

One month after surgery, tissues were histopathologically examined. Spinal tissue surrounding the laminectomy site was cut with a microtome and stained with hematoxylin and eosin and Masson trichrome. Slides were evaluated by a pathologist in a blinded fashion. The extent of epidural fibrosis, fibroblast cell density, cartilage, and bone regeneration was evaluated.

METHODS

Rats were randomly assigned to receive sham surgery, laminectomy, or laminectomy with hemostatic polysaccharide (seven rats per group). Sham surgery that consisted of a skin incision was performed without laminectomy. Laminectomy was performed at the L1 and L2 vertebrae. In the experimental group, the polysaccharide hemostatic material, HaemoCer was placed in the laminectomy area.

RESULTS

The proportion of rats with epidural fibrosis in laminectomized mice (both with and without hemostatic material) was higher than in sham-operated rats (p<.01). There was no difference in fibrosis between the two groups of laminectomized rats (p>.05).

CONCLUSIONS

Our study indicates that hemostatic polysaccharide does not enhance epidural fibrosis following laminectomy in rodents, suggesting that absorbable polysaccharides may be appropriate for use in hemostasis during spinal surgery.

A Flowable Placental Tissue Matrix Allograft in Lower Extremity Injuries: A Pilot Study

Damaged connective tissue commonly leads to lower extremity injuries. These injuries can result in inflammation, reduced mobility, and chronic pain. Conservative treatment may include orthotics, offloading the injury, physical therapy, and/or NSAIDs. If conservative treatment fails, surgical intervention may be required. Even after successful surgery, these procedures often result in reduced joint mobility and tendon or ligament strength. A novel flowable tissue matrix allograft, derived from human placental connective tissue, has recently been made available for minimally invasive treatment of damaged or inadequate tissue  (PX50®, Human Regenerative Technologies LLC, Redondo Beach, CA). Based on the universal role of connective tissue in the body, and its reported antimicrobial, anti-adhesive, and anti-inflammatory properties, we assessed the effects of using this placental tissue matrix in the treatment of a series of lower extremity injuries. In this pilot study, 9 of 10 patients reported pain levels of 2 or less by week four using the VAS pain scale. This short-term pilot study effectively shows that injectable, flowable amniotic allografts can be used for orthopedic sports injuries of the lower extremities.

Effects of cross-linked high-molecular-weight hyaluronic acid on epidural fibrosis: experimental study

OBJECT

Epidural fibrosis is nonphysiological scar formation, usually at the site of neurosurgical access into the spinal canal, in the intimate vicinity of and around the origin of the radicular sheath. The formation of dense fibrous tissue causes lumbar and radicular pain. In addition to radicular symptoms, the formation of scar tissue may cause problems during reoperation. The authors aimed to investigate the effects of cross-linked high-molecular-weight hyaluronic acid (HA), an HA derivative known as HA gel, on the prevention of epidural fibrosis by using histopathological and biochemical parameters.

METHODS

Fifty-six adult female Sprague-Dawley rats were evaluated. The rats were divided into 4 groups. Rats in the sham group (n = 14) underwent laminectomy and discectomy and received no treatment; rats in the control group (n = 14) underwent laminectomy and discectomy and received 0.9% NaCl treatment in the surgical area; rats in the HA group (n = 14) received HA treatment at the surgical area after laminectomy and discectomy; and rats in the HA gel group (n = 14) underwent laminectomy and discectomy in addition to receiving treatment with cross-linked high-molecular-weight HA in the surgical area. All rats were decapitated after 4 weeks, and the specimens were evaluated histopathologically and biochemically. The results were statistically compared using the Mann-Whitney U-test.

RESULTS

Compared with the sham and control groups, the HA and HA gel groups showed significantly lower fibroblast cell density and tissue hydroxyproline concentrations (p < 0.05). There was statistically significant lower dural adhesion and foreign-body reaction between the control and HA gel groups (p < 0.05). Granulation tissue and epidural fibrosis were significantly lower in the HA and HA gel groups compared with the sham group (p < 0.05). There were no significant differences in any histopathological parameters or biochemical values between Groups 3 and 4 (p > 0.05).

CONCLUSIONS

Cross-linked high-molecular-weight HA had positive effects on the prevention of epidural fibrosis and the reduction of fibrotic tissue density. The efficacy of this agent should also be verified in further experimental and clinical studies.

Investigation of efficacy of mitomycin-C, sodium hyaluronate and human amniotic fluid in preventing epidural fibrosis and adhesion using a rat laminectomy model

Study Design

A retrospective study.

Purpose

The aim of this study was to evalute the effects of mitomycin-C, sodium hyaluronate and human amniotic fluid on preventing spinal epidural fibrosis.

Overview of Literature

The role of scar tissue in pain formation is not exactly known, but it is reported that scar tissue causes adhesions between anatomic structures. Intensive fibrotic tissue compresses on anatomic structures and increases the sensitivity of the nerve root for recurrent herniation and lateral spinal stenosis via limiting movements of the root. Also, neuronal atrophy and axonal degeneration occur under scar tissue.

Methods

The study design included 4 groups of rats: group 1 was the control group, groups 2, 3, and 4 receieved antifibrotic agents, mitomycin-C (group 2), sodium hyaluronate (group 3), and human amniotic fluid (group 4). Midline incision for all animals were done on L5 for total laminectomy. Four weeks after the surgery, the rats were sacrificed and specimens were stained with hematoxylin-eosin and photos of the slides were taken for quantitive assesment of the scar tissue.

Results

There was no significant scar tissue in the experimental animals of groups 2, 3, and 4. It was found that there was no significant difference between drug groups, but there was a statistically significant difference between the drug groups and the control group.

Conclusions

This experimental study shows that implantation of mitomycin-C, sodium hyaluronate and human amniotic fluid reduces epidural fibrosis and adhesions after spinal laminectomy in rat models. Further studies in humans are needed to determine the complications of the agents researched.