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

VISTA technique in combination with chorionic allograft for gingival recession coverage: a case series

The vestibular incision subperiosteal tunnel access (VISTA) technique, a minimally invasive procedure, achieves multitooth recession coverage with only a single access incision. Use of fetal membranes such as the amnion and chorion has become increasingly popular in the field of dentistry due to their lack of immunogenicity and added advantage of growth factors. The present case series aimed to provide information regarding the potential advantage of placing a chorionic membrane in combination with the VISTA technique to achieve recession coverage. Eight healthy adult patients presenting with 24 Miller Class I multitooth gingival recession defects were surgically treated with the VISTA technique and a chorionic membrane. The clinical parameters measured at baseline and 1, 3, and 6 months postoperatively were probing depth, clinical attachment level, width of keratinized gingiva, thickness of attached gingiva, and height of gingival recession. A repeated-measures analysis of variance with a post hoc Bonferroni test was carried out to compare the baseline values with the 1-, 3-, and 6-month postoperative values. The mean (SD) height of gingival recession was significantly reduced from 2.04 (0.67) mm at baseline to 0.71 (0.71) mm at 6 months (P < 0.001). In addition, there were statistically significant gains in the clinical attachment level, width of keratinized gingiva, and thickness of attached gingiva from baseline to 6 months postoperatively (P < 0.001). The probing depth remained the same at all measurement times. The VISTA technique provided good results in terms of recession coverage. Although there was an improvement in the gingival biotype, the placement of a chorionic membrane did not provide any advantage in terms of percentage of root coverage.

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.

Comparison of human mesenchymal stromal cells from four neonatal tissues: Amniotic membrane, chorionic membrane, placental decidua and umbilical cord

BACKGROUND

Mesenchymal stromal cells (MSCs) are being investigated as a potential alternative for cellular therapy. This study was designed to compare the biological characteristics of MSCs isolated from amniotic membrane (A-MSCs), chorionic membrane (C-MSCs), placental decidua (D-MSCs) and umbilical cord (UC-MSCs) to ascertain whether any one of these sources is superior to the others for cellular therapy purposes.

METHODS

MSCs were isolated from amniotic membrane, chorionic membrane, umbilical cord and placental decidua. Immunophenotype, differentiation ability, cell size, cell complexity, polarity index and growth kinetics of MSCs isolated from these four sources were analyzed.

RESULTS

MSCs were successfully isolated from all four sources. Surface marker profile and differentiation ability were consistent with human MSCs. C-MSCs in suspension were the smallest cells, whereas UC-MSCs presented the greatest length and least width. A-MSCs had the lowest polarity index and UC-MSCs, as more elongated cells, the highest. C-MSCs, D-MSCs and UC-MSCs exhibited similar growth capacity until passage 8 (P8); C-MSCs presented better lifespan, whereas insignificant proliferation was observed in A-MSCs.

DISCUSSION

Neonatal and maternal tissues can serve as sources of multipotent stem cells. Some characteristics of MSCs obtained from four neonatal tissues were compared and differences were observed. Amniotic membrane was the least useful source of MSCs, whereas chorionic membrane and umbilical cord were considered good options for future use in cell therapy because of the known advantages of immature cells.

Topical Review: Use of Fetal Tissue in Foot and Ankle Surgery

Fetal tissues are well known for their therapeutic potential. They contain numerous growth factors, cytokines, and matrix components that promote regeneration of tissues while downregulating inflammation and scar formation. As a result, use of these treatments has expanded over the previous 20 years throughout various surgical specialties, including orthopaedics. With improved methods of sterilization, processing, and storage, surgeons need to be informed about the potential benefits of fetal tissue in foot and ankle surgery. The aim of this review is to provide a brief historical background, basic anatomy and physiology, and a current review of the literature in regard to chronic wounds, diabetic foot ulcerations, plantar fasciitis, tendon repair, adhesion prevention, nerve repair, and bone healing.

LEVELS OF EVIDENCE

Level V: Expert Opinion.