New dried human amniotic membrane is useful as a substitute for dural repair after skull base surgery

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.

Cerebrospinal fluid leakage complicated by intracranial hematoma and cervical infection following resection of dumbbell schwannoma in the cervical canal: a case report and literature review

BACKGROUND

Haemorrhagic cerebral infarction with cervical infection is a severe and complex complication in spinal surgery. This paper report a case of intracranial hematoma secondary to cerebrospinal fluid leakage after surgery for dumbbell tumor of cervical spine.

CASE PRESENTATIONS

The patient suffered from postoperative cerebrospinal fluid leakage followed by hemorrhagic cerebral infarction, unilateral limb sensorimotor dysfunction and language dysfunction, and was treated conservatively. Combined with cervical infection, the treatment was anti-inflammatory and lumbar puncture drainage. The infection of the patient was cured, and the symptoms related to hemorrhagic cerebral infarction were better than before.

RESULTS

The case showed cerebrospinal fluid leakage after the operation of dumbbell tumor of cervical spine, which caused hemorrhagic cerebral infarction with typical clinical symptoms.

CONCLUSIONS

The risk complications of intracranial hemorrhage and cervical infection should be paid attention to when cerebrospinal fluid loss occurs in patients with cervical dumbbell tumor after surgery.

A robust and biodegradable hydroxyapatite/poly(lactide-co-ε-caprolactone) electrospun membrane for dura repair

Typically occurring after trauma or neurosurgery treatments, dura mater defect and the ensuing cerebrospinal fluid (CSF) leakage could lead to a number of serious complications and even patient's death. Although numerous natural and synthetic dura mater substitutes have been reported, none of them have been able to fulfill the essential properties, such as anti-adhesion, leakage blockage, and pro-dura rebuilding. In this study, we devised and prepared a series of robust and biodegradable hydroxyapatite/poly(lactide-co-ε-caprolactone) (nHA/PLCL) membranes for dura repair via an electrospinning technique. In particular, PLLA/PCL (80/20) was selected for electrospinning due to its mechanical properties that most closely resembled natural dural tissue. Studies by SEM, XRD, water contact angle and in vitro degradation showed that the introduction of nHA would destroy PLCL's crystalline structure, which would further affect the mechanical properties of the nHA/PLCL membranes. When the amount of nHA added increased, so did the wettability and in vitro degradation rate, which accelerated the release of nHA. In addition, the high biocompatibility of nHA/PLCL membranes was demonstrated by in vitro cytotoxicity data. The in vivo rabbit dura repair model results showed that nHA/PLCL membranes provided a strong physical barrier to stop tissue adhesion at dura defects. Meanwhile, the nHA/PLCL and commercial group's CSF had a significantly lower number of inflammatory cells than the control groups, validating the nHA/PLCL's ability to effectively lower the risk of intracranial infection. Findings from H&E and Masson-trichrome staining verified that the nHA/PLCL electrospun membrane was more favorable for fostering dural defect repair and skull regeneration. Moreover, the relative molecular weight of PLCL declined dramatically after 3 months of implantation, according to the results of the in vivo degradation test, but it retained the fiber network structure and promoted tissue growth, demonstrating the good stability of the nHA/PLCL membranes. Collectively, the nHA/PLCL electrospun membrane presents itself as a viable option for dura repair.

Clinical and Radiographic Evaluation of Mineral Trioxide Aggregate and Human Amniotic Membrane Pulpotomy in Primary Molars: A Randomized Clinical Trial

Objectives

To clinically and radiographically compare the outcomes of pulpotomy with mineral trioxide aggregate (MTA) and human amniotic membrane (HAM) in primary molar teeth at 1, 3, 6, and 12 months.

Materials and methods

The study was a randomized clinical trial with two arms. One arm consisted of participants whose pulpotomy was conducted using MTA, called group I, and the other arm, using HAM, was designated group II.

Results

Both MTA and HAM exhibited 100% clinical success. Also, there were no signs of external resorption, periapical bone destruction, or internal resorption in both the MTA and the HAM groups at all four time intervals in this study. However, periodontal ligament widening was seen in 30% of the participants in the MTA group at 1-month and at the 12-month follow-up, whereas in the HAM group, periodontal ligament widening was found to reduce significantly from 22.2% at 1-month to 11.1% at the 12-month follow-up.

Conclusion

The HAM exhibited favorable clinical and radiographic outcomes in the present study.

Clinical significance

Mineral trioxide aggregate is the most preferred choice as a pulpotomy agent for deciduous teeth. However, various drawbacks associated with MTA have been fueling the need for newer, effective agents. HAM is not only easily available, cost-effective, and easy to handle but also favors tissue regeneration. The positive outcome of the present study strongly advocates the use of HAM as an alternative to MTA for pulpotomy in primary teeth.

How to cite this article

Joseph EJ, Rao A, Mahabala KY, et al. Clinical and Radiographic Evaluation of Mineral Trioxide Aggregate and Human Amniotic Membrane Pulpotomy in Primary Molars: A Randomized Clinical Trial. Int J Clin Pediatr Dent 2024;17(6):641-646.

Swim bladder-derived biomaterials: structures, compositions, properties, modifications, and biomedical applications

Animal-derived biomaterials have been extensively employed in clinical practice owing to their compositional and structural similarities with those of human tissues and organs, exhibiting good mechanical properties and biocompatibility, and extensive sources. However, there is an associated risk of infection with pathogenic microorganisms after the implantation of tissues from pigs, cattle, and other mammals in humans. Therefore, researchers have begun to explore the development of non-mammalian regenerative biomaterials. Among these is the swim bladder, a fish-derived biomaterial that is rapidly used in various fields of biomedicine because of its high collagen, elastin, and polysaccharide content. However, relevant reviews on the biomedical applications of swim bladders as effective biomaterials are lacking. Therefore, based on our previous research and in-depth understanding of this field, this review describes the structures and compositions, properties, and modifications of the swim bladder, with their direct (including soft tissue repair, dural repair, cardiovascular repair, and edible and pharmaceutical fish maw) and indirect applications (including extracted collagen peptides with smaller molecular weights, and collagen or gelatin with higher molecular weights used for hydrogels, and biological adhesives or glues) in the field of biomedicine in recent years. This review provides insights into the use of swim bladders as source of biomaterial; hence, it can aid biomedicine scholars by providing directions for advancements in this field.

Comparison of the effects of preservation methods on structural, biological, and mechanical properties of the human amniotic membrane for medical applications

Amniotic membrane (AM), the innermost layer of the placenta, is an exceptionally effective biomaterial with divers applications in clinical medicine. It possesses various biological functions, including scar reduction, anti-inflammatory properties, support for epithelialization, as well as anti-microbial, anti-fibrotic and angio-modulatory effects. Furthermore, its abundant availability, cost-effectiveness, and ethical acceptability make it a compelling biomaterial in the field of medicine. Given the potential unavailability of fresh tissue when needed, the preservation of AM is crucial to ensure a readily accessible and continuous supply for clinical use. However, preserving the properties of AM presents a significant challenge. Therefore, the establishment of standardized protocols for the collection and preservation of AM is vital to ensure optimal tissue quality and enhance patient safety. Various preservation methods, such as cryopreservation, lyophilization, and air-drying, have been employed over the years. However, identifying a preservation method that effectively safeguards AM properties remains an ongoing endeavor. This article aims to review and discuss different sterilization and preservation procedures for AM, as well as their impacts on its histological, physical, and biochemical characteristics.

Biosubstitutes for dural closure: Unveiling research, application, and future prospects of dura mater alternatives

The dura mater, as the crucial outermost protective layer of the meninges, plays a vital role in safeguarding the underlying brain tissue. Neurosurgeons face significant challenges in dealing with trauma or large defects in the dura mater, as they must address the potential complications, such as wound infections, pseudomeningocele formation, cerebrospinal fluid leakage, and cerebral herniation. Therefore, the development of dural substitutes for repairing or reconstructing the damaged dura mater holds clinical significance. In this review we highlight the progress in the development of dural substitutes, encompassing autologous, allogeneic, and xenogeneic replacements, as well as the polymeric-based dural substitutes fabricated through various scaffolding techniques. In particular, we explore the development of composite materials that exhibit improved physical and biological properties for advanced dural substitutes. Furthermore, we address the challenges and prospects associated with developing clinically relevant alternatives to the dura mater.

Dural Reconstruction Materials for the Repairing of Spinal Neoplastic Cerebrospinal Fluid Leaks

Spinal tumors often lead to more complex complications than other bone tumors. Nerve injuries, dura mater defect, and subsequent cerebrospinal fluid (CSF) leakage generally appear in spinal tumor surgeries and are followed by serious adverse outcomes such as infections and even death. The use of suitable dura mater replacements to achieve multifunctionality in fluid leakage plugging, preventing adhesions, and dural reconstruction is a promising therapeutic approach. Although there have been innovative endeavors to manage dura mater defects, only a handful of materials have realized the targeted multifunctionality. Here, we review recent advances in dura repair materials and techniques and discuss the relative merits in both preclinical and clinical trials as well as future therapeutic options. With these advances, spinal tumor patients with dura mater defects may be able to benefit from novel treatments.

Human Amniotic Membrane for Dural Repair and Duraplasty: A Systematic Review of Safety and Efficacy

The use of human amniotic membrane (HAM) has recently gained attention as a promising alternative option for duraplasty due to its superior tensile strength, elasticity, and anti-inflammatory and anti-fibrotic properties, offering greater durability and reliability compared to autologous grafts like the muscle fascia and pericranium. This systematic review aimed to evaluate the complications associated with duraplasty using HAM. We comprehensively searched the PubMed, Scopus, and Web of Science databases for studies on duraplasty with HAM. The eligibility criteria included studies on patients who underwent dural repair with duraplasty using HAM, with or without a control group. Duraplasty involves opening the dura mater, the protective covering of the brain and spinal cord, and using a graft to enlarge the space around the cerebellum. Dual repair, on the other hand, involves repairing the dura mater without opening it and then using a patch to enlarge the space around the cerebellum. Randomized controlled trials, observational studies, case series, and case reports were included, and quality assessment was conducted. Our search yielded 191 articles. Ten studies were included, with a total of 560 participants. The overall incidence of cerebrospinal fluid (CSF) leakage was three (0.63%) out of 478 in the HAM group and three (4.76%) out of 63 in the other methods group (pericranium, temporalis fascia, and biological dural substitutes). Regarding the incidence of postoperative complications, the overall incidence was eight (1.92%) out of 417 in the HAM group and two (8%) out of 25 in the other methods group. The overall incidence of meningitis was one (0.67%) out of 150 in the HAM group and three (10%) out of 30 in the other methods group. In conclusion, duraplasty using HAM may be a safe and effective alternative to traditional methods, with a low incidence of CSF leakage and postoperative complications.

Dehydrated human amnion/chorion membrane use in emergent craniectomies shows minimal dural adhesions

Decompressive craniectomies (DCs) are routinely performed neurosurgical procedures to emergently treat increased intracranial pressure secondary to multiple aetiologies, such as subdural haematoma, epidural haematoma, or malignant oedema in the setting of acute infarction. The DC procedure typically induces epidural fibrosis post-cranial resection, resulting in adherence of the dura to both the brain internally and skin flap externally. This becomes especially problematic in the setting of skull flap replacement for cranioplasty as adherences can lead to bridging vein tear, damage to the underlying brain cortex, and other postoperative complications. Dural adjuvants, which can contribute to decreased rate of adherence formation, can thereby reduce both postoperative cranioplasty complications and operative duration. Dehydrated human amnion/chorion membrane (DHACM) allografts (AMNIOFIX, MIMEDX Group Inc., US) have been shown to reduce the rate of dural scar tissue formation in re-exploration of posterior lumbar interbody fusion operations which require entry into the epidural space. The purpose of this study was to evaluate whether or not the use of DHACM in the setting of emergent craniectomies decreased the rate of dural adhesion formation and subsequent cranioplasty complications. Patients (n=7) who underwent emergent craniectomy and intraoperative placement of DHACM were evaluated during replacement of either an autologous skull cap or a custom-made implant, at which point the degree of adhesions was qualitatively assessed. Placement of DHACM below and on top of the dura resulted in negligible adhesion being found during the defect exposure, and there were no intraoperative complications during cranioplasties. Reported estimated blood loss across the seven patients averaged 64.2ml, total operative time averaged 79.2 minutes, and time dedicated to exposing defect for bone flap placement was <3 minutes.

Hyperdry Human Amniotic Membrane as a Protective Dressing for Open Wounds With Exposed Bowel in Mice

INTRODUCTION

An enteroatmospheric fistula forms when the exposed bowel is perforated with chronic enteric fistula formation. Currently, there is no established preventative method for this condition. Hyperdry (HD) amniotic membrane (AM) can promote early granulation tissue formation on the exposed viscera and is suitable for dressing intractable wounds as it possesses anti-inflammatory, antibacterial, and immunomodulatory properties. This study investigated whether HD-AM promotes early formation of blood vessel-containing granulation tissue for enteroatmospheric fistula treatment.

METHODS

An experimental animal model of an open wound with exposed bowel was developed. A 15 × 20 mm wound was prepared on the abdomen of Institute of Cancer Research mice, and the HD-AM was placed. The mice were assigned to one of the following groups: HD-AM group, in which the stromal layer of the HD-AM was placed in contact with the exposed bowel; HD-AM UD group, in which the epithelial layer of the HD-AM was placed in contact with the exposed bowel; and the HD-AM (-) or control group, in which the HD-AM was not used.

RESULTS

On postoperative days 7 and 14, granulation tissue thickness significantly increased in the HD-AM and HD-AM UD groups compared with that in the HD-AM (-) group. Macrophages accumulated in the HD-AM epithelium only in the HD-AM group. During HD-AM contact, a subset of invading macrophages switched from M1 to M2 phenotype.

CONCLUSIONS

HD-AM is a practical wound dressing with its scaffolding function, regulation of TGF β-1 and C-X-C motif chemokine 5 (CXCL-5), and ability to induce M1-to-M2 macrophage conversion.

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.

Dry preserved multilayered fibroblast cell sheets are a new manageable tool for regenerative medicine to promote wound healing

This study investigated the therapeutic effects of dry-preserved multi-layered fibroblast cell sheets (dry sheets) on cutaneous ulcers. Dry sheets were prepared by air-drying multi-layered fibroblast cell sheets (living sheets) to cease their life activities. Before in vivo application, we tested the release of growth factors into the medium to examine the mechanisms of dry sheets in wound healing. Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were released from both dry and living sheets, while high levels of fibroblast growth factor-2 (FGF-2) and high mobility group box 1 (HMGB1) protein were only from dry sheets. An in vitro fibroblast proliferation assay revealed that the dry sheet eluate significantly enhanced cell proliferation and VEGF and HGF production compared with living sheet eluate. FGF-2-neutralizing antibodies significantly blocked this proliferative response. In wounds created on diabetic mice, the dry sheet-treatment groups using autologous or allogeneic cells showed significantly accelerated wound closure compared with that in the no-treatment group. The storage stability of the dry sheet was better at refrigeration temperature than at room temperature and remained stable for at least 4 weeks. Our data indicated that allogeneic dry sheets represent a promising new tool for regenerative medicine that promotes wound healing.

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.

Effect of hyperdry amniotic membrane in preventing tendon adhesion in a rabbit model

BACKGROUND

No anti-adhesive materials are currently in clinical use for orthopaedic surgery. We developed a hyperdry amniotic membrane (HD-AM) for easy storage and transplantation as amniotic membrane. The purpose of this study was to examine the application of HD-AM to reduce peritendinous adhesions without impairing tendon healing.

METHODS

We randomly divided 3 digits (2nd, 3rd, and 4th digits) from each rabbit into three groups: a tendon repair group; a tendon repair with HD-AM group (HD-AM group); and a control group (cast only). The effects of HD-AM on peritendinous adhesions and tendon healing were examined using microscopic, histological, and mechanical analyses in a rabbit flexor digitorum profundus tendon model.

RESULTS

Adhesions on macroscopic evaluation of the tendon repair site were significantly smaller in the HD-AM group than in the tendon repair group. Little adhesion formation or foreign body reactions were seen by on histologic evaluation in the HD-AM group. Range of motion following tendon repair was significantly better in the HD-AM group than in the tendon repair group. Maximal tensile strength required to pull the tendon from the site of adhesion was significantly smaller in the HD-AM group than in the tendon repair group. As for tendon repair site, no significant difference was seen between the tendon repair and HD-AM groups.

CONCLUSIONS

HD-AM prevented peritendinous adhesion macroscopically, pathologically, and mechanically without impairing the sutured tendon. HD-AM has already been clinically applied in neurosurgery, ophthalmology, and otolaryngology, and clinical application as an anti-adhesive materials may be achieved in the future.

Anal Fistula Human Amniotic Membrane Endosealing (F-HAME): A Proof of Concept Study

The treatment of cryptoglandular anal fistula (AF) is often a challenge for surgeons. Several sphincter-saving procedures have been described as an alternative to fistulotomy, with the common goal of promoting healing and preserve anal continence. The aim of this proof of concept study was to assess the outcomes of human amniotic membrane (HAM) implantation in cryptoglandular transphincteric AF. Two consecutive female were recruited. The primary outcome was clinical healing at 6 months. Secondary outcomes were ultrasonographic healing, complications and reinterventions, AF symptoms, fecal incontinence, psychological impact of treatment, recurrence, development of additional AF, patient satisfaction, and quality of life, as measured using validated questionnaires. Both patients (40 and 54-year-old) previously underwent incision and drainage of anal abscess with concomitant seton placement. HAM implantation was performed as a day case under local anesthesia. No intra- or post-procedural complications occurred. Clinical and radiological healing were not achieved at 6 months. However, the external outlet discharge diminished through time, with sustained improvements in quality of life. Clinical healing occurred at 7 months in both patients. Psychological impact of treatment and patient satisfaction were overall good, with improvements in the PHQ-9, GAD-7, and Short Assessment of Patients Satisfaction. HAM implantation is safe and improves patients' quality of life, progressively leading to clinical healing. Future studies are needed to assess its safety in other etiology of AF.

DUROPLASTY: REVIEW OF MATERIALS AND TECHNIQUES

Introduction. Degenerative disc disease is one of the most common diseases of the musculoskeletal system, characterized by dystrophic changes in the intervertebral disc and vertebral bodies adjacent to it. The main symptoms of this disease are pain and sensory and motor disorders, which, according to various authors, occur in 50–80% of adults. The main objective of the study was to find and implement the optimal set of treatment measures for degenerative disc disease depending on the age of a patient. Materials and Methods. The medical records of inpatients who were treated in the Neurosurgical Department of the Sumy Regional Clinical Hospital in 2019–2020 were analyzed. The course of treatment of 93 patients (61 men and 32 women) was studied. The patients were divided into groups according to their age: young age (under 25) – 13 men and 8 women; middle age (under 60) – 24 men and 19 women; and elderly age (over 60 years) – 18 men and 11 women. The combined use of pathogenetically justified physiotherapeutic measures in the treatment complex is gaining more and more interest. Their distinctive features are physiologic nature, absence of allergic manifestations, the ability to influence most of the pathogenesis of the disease, and the organic combination with other therapeutic factors. Unfortunately, there is an increase in the incidence of temporary incapacitation and progressive course, which often leads to disability and significant financial costs associated with expensive modern methods of diagnosis, treatment, and further provision of employment to patients. The results of our study show that complex treatment including pathogenetic drug therapy, complex paravertebral block, therapeutic physical exercise, and physiotherapy treatment methods provides adequate recovery of spinal function regardless of dystrophic and degenerative changes severity and patient's age. Treatment of degenerative disc disease should be comprehensive and directed at the various symptoms and links of the pathological process.

Applications of materials for dural reconstruction in pre-clinical and clinical studies: Advantages and drawbacks, efficacy, and selections

The dura mater provides a barrier to protect the tissue underneath and cerebrospinal fluid. However, dural defects normally cause cerebrospinal fluid leakage and other complications, such as wound infections, meningitis, etc. Therefore, the reconstruction of dura mater has important clinical significance. Current dural reconstruction materials include: homologous, acellular, natural, synthetic, and composite materials. This review comprehensively summarizes the characteristics and efficacy of these dural substitutes, especially in clinical applications, including the advantages and drawbacks of those from different sources, the host tissue response in pre-clinical studies and clinical practice, and the comparison of these materials across different surgical procedures. Furthermore, the selections of materials for different surgical procedures are highlighted. Finally, the challenges and future perspectives in the development of ideal dural repair materials are discussed.

Immunomodulatory Properties of Amniotic Membrane Derivatives and Their Potential in Regenerative Medicine

PURPOSE OF REVIEW

During the last decades, the field of regenerative medicine has been rapidly evolving. Major progress has been made in the development of biological substitutes applying the principles of cell transplantation, material science, and bioengineering.

RECENT FINDINGS

Among other sources, amniotic-derived products have been used for decades in various fields of medicine as a biomaterial for the wound care and tissue replacement. Moreover, human amniotic epithelial and mesenchymal cells have been intensively studied for their immunomodulatory capacities. Amniotic cells possess two major characteristics that have already been widely exploited. The first is their ability to modulate and suppress the innate and adaptive immunities, making them a true asset for chronic inflammatory disorders and for the induction of tolerance in transplantation models. The second is their multilineage differentiation capacity, offering a source of cells for tissue engineering. The latter combined with the use of amniotic membrane as a scaffold offers all components necessary to create an optimal environment for cell and tissue regeneration. This review summarizes beneficial properties of hAM and its derivatives and discusses their potential in regenerative medicine.

Comparing the results of duraplasty using amniotic membrane versus pericranium as dural graft; concerning CSF leakage and pseudomeningocele

Purpose: In many brain surgeries, dura cannot be primarily repaired and it is necessary to use a graft. Appropriate repair of dura plays a major role in preventing CSF leakage and meningitis. In the cases where sufficient Pericranium is not available for recovery, we need to use graft from other resources. The present study compares the results of amniotic membrane dural graft and pericranium dural graft in terms of CSF leakage and Pseudomeningocele. Materials and methods: This is a semi-empirical research. Thirty cases underwent dural graft with amnion membrane because of inadequate local pericranium for repair. There were 30 other historical cases that had undergone auto-graft dural graft with Pericranium in the same center.Results: The average age of the participants in Pericranium graft group (P, n = 30) and those in amniotic graft group (A, n = 30) was 39.1 ± 15 and 43.9 ± 19 years old, respectively. As for the P and A groups, there were 14 and 17 males, respectively. Two cases of CSF leakage (7%) were observed in P group, while none was reported in A group. There were 3 cases (10%) of meningitis in Pericranium group and 2 cases (7%) were reported in amnion group. Out of 2 cases of meningitis in group P, 2 cases were associated with CSF leak. 5 cases of Hydrocephalus (17%) were observed in group P and 9 cases (30%) were reported in group A. No significant difference was observed between the two groups in any complication. The frequency of hydrocephalus was significantly higher in posterior fossa craniotomy.Conclusion: Amniotic membrane may provide a good source for cases with a large dural defect and can be utilized for all ages. Of course, its application in cases of posterior fossa craniotomy needs to be carefully studied so that the best results may be obtained.

The use of dehydrated amniotic membrane allograft for augmentation of dural repair in transsphenoidal endoscopic endonasal resection of pituitary adenomas

BACKGROUND

In transsphenoidal endoscopic endonasal surgery (TEES), watertight separation of the sinonasal cavity and intracranial compartment is the primary goal of closure. However, even when meticulous closure technique is implemented, cerebrospinal fluid (CSF) leaks, dural scarring, and meningitis may result. Particularly when intraoperative CSF leak occurs, materials that facilitate the creation of a watertight seal that inhibits disease transition and minimizes inflammatory response after durotomy are sought. Dehydrated amniotic membrane (DAM) allograft appears to confer these attributes as studies have shown it augments epithelialization, facilitates wound healing, and minimizes and impedes bacterial growth. We detail the use of DAM allograft to augment sellar closures after TEES.

METHODS

We conducted a feasibility study, retrospectively reviewing our institution's database of TEES for resection of pituitary adenomas in which DAM was utilized to supplement sellar closure.

RESULTS

One hundred twenty transsphenoidal surgery cases with DAM were used during sellar closure, with a 49.2% intraoperative CSF leak rate. Of this cohort, two patients experienced postoperative CSF leak (1.7%), and no patients developed meningitis. CSF leak rate for TEES-naïve patients was 0.9%.

CONCLUSIONS

This feasibility study demonstrates that dehydrated amniotic membrane allograft can be safely utilized as an adjunct during sellar closures for TEES for pituitary adenoma resection with very low rates of CSF leak and meningitis.

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.

Implantation of amniotic membrane over pancreatic anastomosis after pancreaticoduodenectomy: report of the first case

The amniotic membrane (AM) has an increasing role as a scaffold for tissue repair due to its unique biological properties. The implantation of AM on pancreatic anastomosis after pancreaticoduodenectomy might improve the anastomotic healing and strengthen its structure, however has never been used in pancreatic surgery. We present the first application of AM after a pancreaticoduodenectomy was performed for a malignant tumor of the pancreatic head. After completing the pancreatic anastomosis, the AM was placed around the pancreatic anastomosis and fixed to it with single stiches. The AM, due to its physical characteristics, could be easily manipulated and adapted to the pancreatic anastomosis. This interesting and unique case shows that covering a pancreatic anastomosis with the AM is safe and technically feasible. The AM has no adverse effects while it may eventually provide a beneficial impact over the anastomotic healing.

Research and application progress on dural substitutes

Dural defects are a common problem in clinical practice, and various types of dural substitutes have been used to deal with dural defects. These play an important role in dural repair. Dural substitutes have gradually reached researchers, neurosurgeons, and patients for approval. This article summarizes the structural characteristics of the dura mater and its regeneration after injury, and reviews the state of progress in research and application. It will provide a reference for the development and application of dural substitutes.

Meta-analysis of the use of amniotic membrane to prevent recurrence of intrauterine adhesion after hysteroscopic adhesiolysis

BACKGROUND

Various adjuvant therapies have failed to improve clinical symptoms and pregnancy rates among patients with moderate-to-severe intrauterine adhesion.

OBJECTIVES

To evaluate the ability of amniotic membrane to prevent the recurrence of intrauterine adhesion after hysteroscopic adhesiolysis.

SEARCH STRATEGY

The Cochrane Library, Embase, and PubMed databases were searched for articles published before December 31, 2017, using the terms: ("amnion") and ("intrauterine adhesions" or "Asherman syndrome" or "IUA" or "endometrial injury" or "uterine adhesion" or "hysteroscopic" or "hysteroscopic adhesiolysis").

SELECTION CRITERIA

Randomized controlled trials of amniotic membrane therapy after hysteroscopic adhesiolysis.

DATA COLLECTION AND ANALYSIS

Four studies were included in the meta-analysis (300 patients in total). Dichotomous outcomes were expressed as relative risk (RR) with 95% confidence intervals (CIs). Continuous variables were expressed as mean difference.

MAIN RESULTS

Amniotic membrane increased menstrual blood volume after hysteroscopic adhesiolysis (mean difference 6.15, 95% CI 4.20-8.11; P<0.001). By contrast, this treatment did not affect the rates of intrauterine adhesion recurrence (RR 0.84, 95% CI 0.61-1.16; P=0.290); pregnancy (RR 1.40, 95% CI 0.78-2.50; P=0.260); or spontaneous abortion (RR 0.88, 95% CI 0.38-1.99; P=0.750).

CONCLUSIONS

The use of amniotic membrane increased menstrual blood volume but failed to improve other measures assessed in the current meta-analysis.

Homologous cryopreserved amniotic membrane in the repair of myelomeningocele: preliminary experience

OBJECTIVE

Surgical management of spinal dysraphism often requires the use of dural substitutes. Amniotic membrane (AM) has drawn the interest of clinicians for its valuable concentration of cytokines and factors capable of promoting wound healing, re-epithelialization, inhibiting fibrosis and regulating angiogenesis. These beneficial qualities could make AM an interesting dural substitute for spina bifida repair. In this study, we describe the use of banked homologous AM as a dural substitute for the repair of spinal dysraphism in newborns. Our purpose is to test the mechanical characteristics, as well as the safety and effectiveness of AM in preventing postoperative complications and re-tethering.

METHODS

The AM patch was carefully detached from the chorion of donors undergoing caesarean section, rinsed in saline solution, and cryopreserved in liquid nitrogen. Five newborns were treated using AM: three affected by open spinal dysraphism and two by spina bifida occulta. The AM patch was used as a dural substitute with two different positions and purposes: the amnion-side down covering the placode to prevent adhesions or placed extradurally facing the dura to avoid scarring and facilitating the sliding of the dural sac itself under the extradural tissue layers.

RESULTS

No adverse events occurred, and the surgical wounds healed without complications. MRI scans taken at 3 and 6 months after surgery showed a satisfying de-tethering of the spinal cord with no obvious evidence of new adherence formation.

CONCLUSIONS

We present a multimodal interposition technique using AM as a reconstructive and anti-adhesive tissue for the treatment of open myelomeningocele (MMC) and lipomeningocele (LMC) treatment. In our experience, AM proved its efficacy in restoring the dural sac integrity without complications. We support the use of AM as a promising dural substitute, speculating on how the use of AM could potentially change reconstructive strategies for spinal dysraphism.

The use of dehydrated amniotic membrane allograft for augmentation of dural closure in craniotomies and endoscopic endonasal transphenoidal surgeries

BACKGROUND

Primary watertight dural closure is the preferred method of postcraniotomy dural repair. However, even when ideal technique is implemented, postoperative infection, cerebrospinal fluid (CSF) leaks, pseudomeningoceles, and dural scarring are possible complications. For this reason, materials that augment the dura's ability to create a watertight seal, prevent disease transmission, and inhibit inflammatory response are sought. Dehydrated amniotic membrane (DAM) allograft appears to fulfil these requirements as it has several beneficial properties that aid wound healing, including promotion of epithelialization, scar tissue prevention, and inhibition of bacterial growth. We provide the literature's first description of the use of DAM allograft to supplement dural closures for craniotomies and transsphenoidal surgeries.

METHODS

We conducted a pilot study, retrospectively reviewing our institution's database of craniotomies and transsphenoidal surgeries that utilized DAM to augment dural closure.

RESULTS

One hundred fifty-five cases, including 102 new craniotomies for supratentorial lesions, one re-do craniotomy for supratentorial recurrent glioma, 18 craniotomies for infratentorial lesions, 1 craniotomy for anterior skull base schwannoma, 32 transphenoidal surgeries, and 1 combined craniotomy and transnasal endoscopic surgery, used DAM allograft to augment dural closure. Only one complication occurred (0.6% complication rate), which was a superficial wound infection requiring washout without craniectomy. No CSF leaks occurred.

CONCLUSIONS

This pilot study demonstrates that dehydrated amniotic membrane allograft can be safely utilized as an adjunct during dural closures for craniotomies and transsphenoidal surgeries.

The Use of Dehydrated Amniotic Membrane Allograft for the Augmentation of Dural Repair in Craniotomies

Background: In cranial neurosurgery, primary watertight dural closure is the standard method of post-craniotomy dural repair. However, cerebrospinal fluid (CSF) leaks, pseudomeningoceles, postoperative infections, and dural scarring are possible complications, even when a meticulous technique is implemented. For this reason, materials that enhance the dura’s ability to create a watertight seal, inhibit the inflammatory response, and prevent disease transmission are sought. Dehydrated amniotic membrane (DAM) allograft appears to facilitate these properties, as studies have shown that it improves wound healing, prevents scar tissue formation, promotes epithelialization, and inhibits bacterial growth. We detail the use of a DAM allograft to augment dural closures for craniotomies.

Methods: We conducted a pilot study, retrospectively reviewing our institution’s database of craniotomies that utilized DAM to supplement dural closure.

Results: A total of 122 cases, including 18 initial craniotomies for infratentorial lesions, 102 initial craniotomies for supratentorial lesions, one re-do craniotomy for supratentorial recurrent glioma, and one craniotomy for an anterior skull base schwannoma used a DAM allograft to augment dural closure. Only one complication occurred (0.8% complication rate), which was a superficial wound infection requiring washout without craniectomy. No CSF leaks occurred.

Conclusions: This pilot study demonstrates that dehydrated amniotic membrane allograft can be safely utilized as an adjunct during dural closures for craniotomies.

Human Perinatal-Derived Biomaterials

Human perinatal tissues have been used for over a century as allogeneic biomaterials. Due to their advantageous properties including angiogenecity, anti-inflammation, anti-microbial, and immune privilege, these tissues are being utilized for novel applications across wide-ranging medical disciplines. Given continued clinical success, increased adoption of perinatal tissues as a disruptive technology platform has allowed for significant penetration into the multi-billion dollar biologics market. Here, we review current progress and future applications of perinatal biomaterials, as well as associated regulatory issues.

Cytokine expression and ultrastructural alterations in fresh-frozen, freeze-dried and γ-irradiated human amniotic membranes

The aim of this work was to compare the effects on human amniotic membrane of freeze-drying and γ-irradiation at doses of 10, 20 and 30 kGy, with freezing. For this purpose, nine cytokines (interleukin 10, platelet-derived growth factor-AA, platelet-derived growth factor-BB, basic fibroblast growth factor, epidermal growth factor, transforming growth factor beta 1, and tissue inhibitors of metalloproteinase-1, -2, and -4) were titrated in 5 different preparations for each of 3 amniotic membranes included in the study. In addition, the extracellular matrix structure of each sample was assessed by transmission electron microscopy. While freeze-drying did not seem to affect the biological structure or cytokine content of the different amniotic membrane samples, γ-irradiation led to a significant decrease in the tissue inhibitors of metalloproteinase-4, basic fibroblast growth factor and epidermal growth factor, and induced structural damage to the epithelium, basement membrane and lamina densa. The higher the irradiation dose the more severe the damage to the amniotic membrane structure. In conclusion, the Authors recommend processing amniotic membrane under sterile conditions to guarantee safety at every step rather than final sterilization with γ-irradiation, thereby avoiding alteration to the biological characteristics of the amniotic membrane.

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.

Banked Fascia Lata in Sellar Dura Reconstruction after Endoscopic Transsphenoidal Skull Base Surgery

Objectives Cerebrospinal fluid (CSF) leakage is an undesirable complication of transsphenoidal skull base surgery. The issue of the most appropriate sellar dura repair remains unresolved, although a multilayer technique using autologous fascia lata is widely used. We describe the novel application of a homologous banked fascia lata graft as an alternative to an autologous one in the reconstruction of sellar dura defects in endoscopic transsphenoidal surgery. Design The clinical records of patients who underwent endoscopic transsphenoidal surgery at our department from June 2012, when we started using homologous fascia lata, up to July 2014 were reviewed retrospectively. The data concerning diagnosis, reconstruction technique, and surgical outcome were analyzed. Results We treated 16 patients successfully with banked fascia lata. Twelve patients presented intraoperative CSF leakage, and four patients were treated for postoperative rhinoliquorrhea. Banked fascia lata was used in a single-to-multilayer technique, depending on the anatomical features of the defect and of the sellar floor. No complications or failures in sella reconstruction occurred. Conclusion A banked fascia lata graft proved reliable and safe in providing an effective sellar dura reconstruction. Used in a multilayer strategy, it should be considered a viable alternative to an autologous fascia lata graft.

Bacterial cellulose membranes used as artificial substitutes for dural defection in rabbits

To improve the efficacy and safety of dural repair in neurosurgical procedures, a new dural material derived from bacterial cellulose (BC) was evaluated in a rabbit model with dural defects. We prepared artificial dura mater using bacterial cellulose which was incubated and fermented from Acetobacter xylinum. The dural defects of the rabbit model were repaired with BC membranes. All surgeries were performed under sodium pentobarbital anesthesia, and all efforts were made to minimize suffering. All animals were humanely euthanized by intravenous injection of phenobarbitone, at each time point, after the operation. Then, the histocompatibility and inflammatory effects of BC were examined by histological examination, real-time fluorescent quantitative polymerase chain reaction (PCR) and Western Blot. BC membranes evenly covered the surface of brain without adhesion. There were seldom inflammatory cells surrounding the membrane during the early postoperative period. The expression of inflammatory cytokines IL-1β, IL-6 and TNF-α as well as iNOS and COX-2 were lower in the BC group compared to the control group at 7, 14 and 21 days after implantation. BC can repair dural defects in rabbit and has a decreased inflammatory response compared to traditional materials. However, the long-term effects need to be validated in larger animals.

The clinical applications of human amnion in plastic surgery

Since the early 1900s, human amnion has been applied to a wide variety of clinical scenarios including burns, chronic ulcers, dural defects, intra-abdominal adhesions, peritoneal reconstruction, genital reconstruction, hip arthroplasty, tendon repair, nerve repair, microvascular reconstruction, corneal repair, intra-oral reconstruction and reconstruction of the nasal lining and tympanic membrane. Amnion epithelial and mesenchymal cells have been shown to contain a variety of regulatory mediators that result in the promotion of cellular proliferation, differentiation and epithelialisation and the inhibition of fibrosis, immune rejection, inflammation and bacterial invasion. The full repertoire of biological factors that these cells synthesise, store and release and the mechanisms by which these factors exert their beneficial effects are only now being fully appreciated. Although many commercially available biological and synthetic alternatives to amnion exist, ethical, religious, and financial constraints may limit the widespread utilisation of these products. Amnion is widely available, economical and is easy to manipulate, process and store. Although many clinical applications are of historical interest only, amnion offers an alternative source of multi-potent or pluripotent stem cells and therefore may yet have a great deal to offer the plastic surgery and regenerative medicine community. It is the purpose of this article to review the clinical applications of human amnion relevant to plastic surgery.

Intraoral application of hyperdry amniotic membrane to surgically exposed bone surface

Hyperdry amniotic membrane, a novel preservable material derived from the human amnion, has been introduced clinically in ophthalmology and other fields. This membrane is available as a wound dressing material for surgical wounds of the tongue and buccal mucosa but has not been used on wounds of the alveolar mucosa. This paper reports 2 cases in which intraoral alveolar wounds with bone exposure were successfully treated with the use of hyperdry amniotic membrane: a 74-year-old woman with gingival leukoplakia of the edentulous mandible, and a 43-year-old man who underwent vestibuloplasty of the reconstructed mandible. The results indicate that the hyperdry amniotic membrane is a useful dressing material, not only for soft tissue wounds, but also for exposed bone in the oral cavity.