HLA typing of amniotic fluid cells

Epicardial placement of human placental membrane protects from heart injury in a swine model of myocardial infarction

Cardiac ischemic reperfusion injury (IRI) is paradoxically instigated by reestablishing blood-flow to ischemic myocardium typically from a myocardial infarction (MI). Although revascularization following MI remains the standard of care, effective strategies remain limited to prevent or attenuate IRI. We hypothesized that epicardial placement of human placental amnion/chorion (HPAC) grafts will protect against IRI. Using a clinically relevant model of IRI, swine were subjected to 45 min percutaneous ischemia followed with (MI + HPAC, n = 3) or without (MI only, n = 3) HPAC. Cardiac function was assessed by echocardiography, and regional punch biopsies were collected 14 days post-operatively. A deep phenotyping approach was implemented by using histological interrogation and incorporating global proteomics and transcriptomics in nonischemic, ischemic, and border zone biopsies. Our results established HPAC limited the extent of cardiac injury by 50% (11.0 ± 2.0% vs. 22.0 ± 3.0%, p = 0.039) and preserved ejection fraction in HPAC-treated swine (46.8 ± 2.7% vs. 35.8 ± 4.5%, p = 0.014). We present comprehensive transcriptome and proteome profiles of infarct (IZ), border (BZ), and remote (RZ) zone punch biopsies from swine myocardium during the proliferative cardiac repair phase 14 days post-MI. Both HPAC-treated and untreated tissues showed regional dynamic responses, whereas only HPAC-treated IZ revealed active immune and extracellular matrix remodeling. Decreased endoplasmic reticulum (ER)-dependent protein secretion and increased antiapoptotic and anti-inflammatory responses were measured in HPAC-treated biopsies. We provide quantitative evidence HPAC reduced cardiac injury from MI in a preclinical swine model, establishing a potential new therapeutic strategy for IRI. Minimizing the impact of MI remains a central clinical challenge. We present a new strategy to attenuate post-MI cardiac injury using HPAC in a swine model of IRI. Placement of HPAC membrane on the heart following MI minimizes ischemic damage, preserves cardiac function, and promotes anti-inflammatory signaling pathways.

A prospective study of 20 foot and ankle wounds treated with cryopreserved amniotic membrane and fluid allograft

We reviewed the background information and previous clinical studies that considered the use of allogeneic amniotic tissue and fluid (granulized amniotic membrane and amniotic fluid) in the treatment of chronic diabetic foot wounds. This innovation represents a relatively new approach to wound management by delivering a unique allograft of live human cells in a nonimmunogenic structural tissue matrix. Developed to fill soft tissue defects and bone voids and to convey antimicrobial and anti-inflammatory capabilities, granulized amniotic membrane and amniotic fluid does not require fetal death, because its procurement is performed with maternal consent during birth. In the present investigation, 20 chronic wounds (20 patients) that had been treated with standard wound therapy for a mean of 36.6 ± 31.58 weeks and with a mean baseline area of 10.15 ± 19.54 cm(2) were followed up during a 12-week observation period or until they healed. A total of 18 of the wounds (90%) healed during the 12-week observation period, and none of the wounds progressed to amputation. From our experience with the patients in the present case series, we believe that granulized amniotic membrane and amniotic fluid represents a useful option for the treatment of chronic diabetic foot wounds.

Assessment of processed human amniotic membrane as a protective barrier in rat model of sciatic nerve injury

Following nerve injury, scar formation is thought to be a considerable impediment to axonal regeneration at the nerve injury site. Nerve wrapping can protect the regenerating axons, and human amniotic membrane (HAM) derived from human placenta is an effective material for that purpose. The impact of nerve wrapping with HAM on functional recovery after nerve injuries, especially after autograft repair of long gap lesions, has not been comprehensively investigated. In the current study, we investigated whether the application of HAM as a nerve wrap to a 10mm segment of transected and repaired nerve would reduce scar formation and permit better axonal regeneration and/or functional recovery in rats. The outcome was assessed with morphological and functional measures. We found that nerves wrapped with HAM had significantly fewer adhesions and less scar formation than controls. Although the final outcome, both functionally and morphologically, was not significantly improved by wrapping the nerve with HAM, the observed decrease in adhesions and scar formation might help the nerve retain its mobility and thus prevent traction injury and ischemia, which are caused by nerve tethering to the adjacent tissue during the healing process.

Improving electrophysiologic and histologic outcomes by photochemically sealing amnion to the peripheral nerve repair site

BACKGROUND

The surgical approach used today in the repair of peripheral nerve injuries rarely achieves full functional recovery. This study determines whether isolation of the nerve repair site using photochemical tissue bonding (PTB) in combination with human amniotic membrane can improve both functional and histologic recovery.

METHODS

New Zealand white rabbits (n = 24) underwent transection of the right common peroneal nerve. Epineural nerve repair was performed using 10-0 nylon sutures. The repair site was then wrapped in a cuff of human amniotic membrane, which either was secured with sutures or sealed using PTB. Standard neurorrhaphy alone was assessed as a control group. Functional recovery was recorded at 30-day intervals postoperatively by electrophysiologic assessment. At 120 days, animals were killed humanely and nerves harvested for histomorphometry.

RESULTS

Nerves treated with amnion wraps and sealed with PTB demonstrated a statistically significant improvement across both functional and histologic parameters. Functional recovery, as measured by repeated electrophysiologic studies over time, revealed a 26.2% improvement over standard neurorrhaphy alone (P < .05). Nerves treated with PTB-sealed amnion wraps had significantly greater (P < .001) axon (5.08 +/- 1.06 microm) and fiber diameters (7.46 +/- 1.37 microm), as well as myelin thickness (2.39 +/- 0.7 microm) and the g ratio (axon diameter/fiber diameter ratio; 0.68 +/- 0.07) distal to the repair site compared to standard neurorrhaphy alone (4.98 +/- 1.81 microm, 6.77 +/- 1.94 microm, 1.79 +/- 0.42 microm, and 0.71 +/- 0.09, respectively).

CONCLUSION

Isolation of the repair site using a photochemically sealed amnion wrap improves electrophysiologic and histologic recovery compared to standard suture neurorrhaphy.

Photochemical sealing improves outcome following peripheral neurorrhaphy

INTRODUCTION

Peripheral nerve transection initiates a complex molecular response in the severed nerve endings, resulting in the release of neurotrophic and neurotropic factors that are central to axonal survival and regeneration. In this study we tested the hypothesis that sealing the neurorrhaphy site from the surrounding environment using a photochemically bonded nerve wrap would optimize the endoneural environment and enhance regeneration and nerve function recovery.

MATERIALS AND METHODS

Adult rats underwent unilateral sciatic nerve transection and standard epineural nerve repair. The repair site was wrapped with amniotic membrane or autologous vein and then was either sealed using photochemical tissue bonding (PTB) or secured with sutures. Photochemical sealing without a wrap was also carried out. Functional recovery was assessed at 2-wk intervals using walking track analysis and nerve histomorphometry was assessed at 12 wk.

RESULTS

Treating nerves with PTB-sealed amnion significantly improved functional recovery and increased distal axon and fiber diameters and myelin thickness compared to nerves treated with standard neurorrhaphy alone. Direct PTB sealing of the repair site also improved function. Neither amnion secured with sutures nor vein wraps exhibited improved functional or histological recovery compared to standard neurorrhaphy.

CONCLUSIONS

These results suggest that sealing the peripheral nerve repair site with amnion using a photochemical technique may lead to earlier restoration of neural homeostasis and consequent enhanced repair of nerve injury.

Gamma interferon induces detectable serological and functional expression of DR and DP but not DQ antigens on cultured amniotic fluid cells

Cultured amniotic fluid cells, which are used for HLA typing studies for the prenatal diagnosis of HLA linked diseases and for prenatal determination of paternity, usually contain mixtures of fibroblastic and epithelioid cells. Cells of both types lack constitutive expression of HLA class II antigens, but these can be induced by pretreatment with gamma interferon. Both serological and functional studies indicate that detectable levels of DR and DP but not DQ antigens can be thereby induced. DR and DP cannot, however, be induced on chorionic villus cells.

HLA-D and -DR antigens on human amniotic fluid cells. II. Heterogeneous expression of HLA-DR and other cell surface markers

To evaluate further the feasibility of HLA typing for prenatal diagnosis, we tested human amniotic fluid cells (AFC), known to express HLA-A, -B, and -C antigens, for the presence of HLA-DR antigens using type-specific antisera in the microcytotoxicity assay and a monoclonal antibody directed against the common HLA-DR structure (cDR) in indirect immunofluorescence. Prenatal typing of HLA-DR on AFC in the microcytotoxicity test was possible in only one out of eight families studied. The detected DR2 antigen was confirmed by postnatal typings of cord blood lymphocytes. Thereafter, 23 different AFC cultures were tested with monoclonal antibodies in indirect immunofluorescence. Only six cultures were partially positive (23-35% fluorescent cells) with the monoclonal cDR antibody while all AFC cultures demonstrated strong positive fluorescence (68-100%) with a monoclonal antibody against the common HLA-A, -B, and -C structure (cHLA). These data suggest that only a small subpopulation of AFC expresses class II (HLA-DR) antigens in contrast to the nearly ubiquitous expression of class I (HLA-A, -B, and -C) antigens. Furthermore, the heterogeneous expression of cell surface antigens within the various AFC cultures was substantiated with monoclonal antibodies directed toward cell surface antigens of the OKT, OKM, and Lyt series that have been found to be characteristic for subpopulations of lymphoid and hemapoetic cells. Thus, at present, HLA-DR typing is not reliable for prenatal diagnosis.