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Scanning electron microscopic assessment on surface morphology of preserved human amniotic membrane after gamma sterilisation

Ab Hamid SS, Zahari NK, Yusof N, Hassan A

Cell Tissue Bank, 2014 Mar;15(1):15-24.
PMID: 23187886 DOI: 10.1007/s10561-012-9353-x

Human amniotic membrane that has been processed and sterilised by gamma irradiation is widely used as a biological dressing in surgical applications. The morphological structure of human amniotic membrane was studied under scanning electron microscopy (SEM) to assess effects of gamma radiation on human amniotic membrane following different preservation methods. The amniotic membrane was preserved by either air drying or submerged in glycerol before gamma irradiated at 15, 25 and 35 kGy. Fresh human amniotic membrane, neither preserved nor irradiated was used as the control. The surface morphology of glycerol preserved amnion was found comparable to the fresh amniotic membrane. The cells of the glycerol preserved was beautifully arranged, homogonous in size and tended to round up. The cell structure in the air dried preserved amnion seemed to be flattened and dehydrated. The effects of dehydration on intercellular channels and the microvilli on the cell surface were clearly seen at higher magnifications (10,000×). SEM revealed that the changes of the cell morphology of the glycerol preserved amnion were visible at 35 kGy while the air dried already changed at 25 kGy. Glycerol preservation method is recommended for human amniotic membrane as the cell morphological structure is maintained and radiation doses lower than 25 kGy for sterilization did not affect the appearance of the preserved amnion.

Matched MeSH terms: Amnion/radiation effects*; Amnion/transplantation*
Oral prostaglandin e2 and amniotomy for induction of labour

Adeeb N, Fong TN

Med J Malaysia, 1974 Jun;28(4):263-6.
PMID: 4278401
Matched MeSH terms: Amnion/surgery
Fulltext Collagen type I promotes osteogenic differentiation of amniotic membrane-derived mesenchymal stromal cells in basal and induction media

Akhir HM, Teoh PL

Biosci Rep, 2020 12 23;40(12).
PMID: 33245097 DOI: 10.1042/BSR20201325

Collagen has been widely shown to promote osteogenesis of bone marrow mesenchymal stromal cells (BM-MSCs). Due to the invasive procedure of obtaining BM-MSCs, MSCs from other tissues have emerged as a promising alternative for regenerative therapy. MSCs originated from different sources, exhibiting different differentiation potentials. Therefore, the applicability of collagen type I (COL), combining with amniotic membrane (AM)-MSCs was examined through proliferation and differentiation assays together with the expression of surface markers and genes associated with stemness and differentiation under basal or induction conditions. No increase in cell growth was observed because AM-MSCs might be directed toward spontaneous osteogenesis. This was evidenced by the calcium deposition and elevated expression of osteogenic genes when AM-MSCs were cultured in collagen plate with basal media. Under the osteogenic condition, reciprocal expression of OCN and CEBPA suggested a shift toward adipogenesis. Surprisingly, adipogenic genes were not elevated upon adipogenic induction, although oil droplets deposition was observed. In conclusion, our findings demonstrated that collagen causes spontaneous osteogenesis in AM-MSCs. However, the presence of exogenous inductors could shift the direction of adipo-osteogenic gene regulatory network modulated by collagen.

Matched MeSH terms: Amnion/cytology; Amnion/drug effects*; Amnion/metabolism
Fulltext A Preliminary Study of Human Amniotic Membrane as a Potential Chondrocyte Carrier

Boo, L., Sofiah, S., Selvaratnam, L., Tai, C.C., Pingguan-Murphy, B., Kamarul, T.

Malays Orthop J, 2009;3(2):16-23.
MyJurnal

Purpose:To investigate the feasibilty of using processed human amniotic membrane (HAM) to support the attachment and proliferation of chondrocytes in vitro which it turn can be utilised as a cell delivery vehicle in tissue engineering applications. Methods: Fresh HAM obtained from patients undergoing routine elective ceasarean sections was harvested., processed and dried using either freez drying (FD) or air drying (AD) methods prior to sterilisation by gamma irradiation. Isolated, processed and characterised rabbit autologous chondrolytes were seeded on processsed HAM and cultured for up to three weeks. Cell attachment and proliferation were examined qualitatively using inverted brightfield microcospy. Results: Processed HAM appeared to allow cell attachment when implanted with chrondocytes. Although cells seeded on AD and FD HAM did not appear to attach as strongly as those seeded on glycerol preserved intact human amniotic membrane, these cells to be proliferated in cell culture conditions. Conclusion: Prelimanary results show that processed HAM chondrocyte attachment and proliferation.

Matched MeSH terms: Amnion
Dried irradiated human amniotic membrane as a biological dressing for facial burns--a 7-year case series

Bujang-Safawi E, Halim AS, Khoo TL, Dorai AA

Burns, 2010 Sep;36(6):876-82.
PMID: 20236771 DOI: 10.1016/j.burns.2009.07.001

Facial burns are common and have a significant impact on patient function and psychosocial well being. Human amnion has been used for many years as a temporary biological wound dressing in the management of partial thickness burns. The observed advantages of human amnion treatment include pain relief, ease of use, prevention of infection and acceleration of wound healing.

Matched MeSH terms: Amnion/transplantation*
Organotypic culture of human amnion cells in air-liquid interface as a potential substitute for skin regeneration

Fatimah SS, Chua K, Tan GC, Azmi TI, Tan AE, Abdul Rahman H

Cytotherapy, 2013 Aug;15(8):1030-41.
PMID: 23830235 DOI: 10.1016/j.jcyt.2013.05.003

The aim of the present study was to evaluate the effects of air-liquid interface on the differentiation potential of human amnion epithelial cells (HAECs) to skin-like substitute in organotypic culture.

Matched MeSH terms: Amnion/cytology*
Effects of epidermal growth factor on the proliferation and cell cycle regulation of cultured human amnion epithelial cells

Fatimah SS, Tan GC, Chua KH, Tan AE, Hayati AR

J Biosci Bioeng, 2012 Aug;114(2):220-7.
PMID: 22578596 DOI: 10.1016/j.jbiosc.2012.03.021

Human amnion epithelial cells (HAECs) hold great promise in tissue engineering for regenerative medicine. Large numbers of HAECs are required for this purpose. Hence, exogenous growth factor is added to the culture medium to improve epithelial cells proliferation. The aim of the present study was to determine the effects of epidermal growth factor (EGF) on the proliferation and cell cycle regulation of cultured HAECs. HAECs at P1 were cultured for 7 days in medium containing an equal volume mix of HAM's F12: Dulbecco's Modified Eagles Medium (1:1) supplemented with different concentrations of EGF (0, 5, 10, 20, 30 and 50 ng/ml EGF) in reduced serum. Morphology, growth kinetics and cell cycle analysis using flow cytometry were assessed. Quantitative gene expression for cell cycle control genes, pluripotent transcription factors, epithelial genes and neuronal genes were also determined. EGF enhanced HAECs proliferation with optimal concentration at 10 ng/ml EGF. EGF significantly increased the proportion of HAECs at S- and G2/M-phase of the cell cycle compared to the control. At the end of culture, HAECs remained as diploid cells under cell cycle analysis. EGF significantly decreased the mRNA expression of p21, pRb, p53 and GADD45 in cultured HAECs. EGF also significantly decreased the pluripotent genes expression: Oct-3/4, Sox2 and Nanog; epithelial genes expression: CK14, p63, CK1 and Involucrin; and neuronal gene expression: NSE, NF-M and MAP 2. The results suggested that EGF is a strong mitogen that promotes the proliferation of HAECs through cell cycle regulation. EGF did not promote HAECs differentiation or pluripotent genes expression.

Matched MeSH terms: Amnion/cytology*
Value of human amniotic epithelial cells in tissue engineering for cornea

Fatimah SS, Ng SL, Chua KH, Hayati AR, Tan AE, Tan GC

Hum. Cell, 2010 Nov;23(4):141-51.
PMID: 21166885 DOI: 10.1111/j.1749-0774.2010.00096.x

Human amniotic epithelial cells (hAECs) are potentially one of the key players in tissue engineering due to their easy availability. The aim of the present study was to develop an optimal isolation and transportation technique, as well as to determine the immunophenotype and epithelial gene expression of hAECs. Amnion was mechanically peeled off from the chorion and digested with trypsin-ethylenediaminetetraacetic acid. The isolated hAECs were cultured in medium containing 10 ng/mL epidermal growth factor until P4. The epithelial gene expression, cell surface antigen and protein expression of hAECs were analyzed by quantitative polymerase chain reaction, flow cytometry and immunocytochemistry. hAECs were also cultured in adipogenic, osteogenic and neurogenic induction media. The best cell yield of hAECs was seen in the digestion of 15 pieces of amnion (2 × 2 cm) and isolated 30 min after digestion with trypsin. F12:Dulbecco's modified eagle medium was the best medium for short term storage at 4 °C. hAECs expressed CD9, CD44, CD73 and CD90, and negligibly expressed CD31, CD34, CD45 and CD117. After serial passage, CK3, CK19 and involucrin gene expressions were upregulated, while p63, CK1 and CK14 gene expressions were downregulated. Sustained gene expressions of integrin β1 and CK18 were observed. At initial culture, these cells might have stem-like properties. However, they differentiated after serial passage. Nonetheless, hAECs have epithelial stem cell characteristics and have the potential to differentiate into corneal epithelial cells. Further investigations are still needed to elucidate the mechanism of differentiation involved and to optimize the culture condition for long term in vitro culture.

Matched MeSH terms: Amnion/cytology*
Effects of keratinocyte growth factor on skin epithelial differentiation of human amnion epithelial cells

Fatimah SS, Tan GC, Chua K, Tan AE, Nur Azurah AG, Hayati AR

Burns, 2013 Aug;39(5):905-15.
PMID: 23273814 DOI: 10.1016/j.burns.2012.10.019

The aim of the present study was to determine the effects of KGF on the differentiation of cultured human amnion epithelial cells (HAECs) towards skin keratinocyte. HAECs at passage 1 were cultured in medium HAM's F12: Dulbecco's Modified Eagles Medium (1:1) supplemented with different concentrations of KGF (0, 5, 10, 20, 30 and 50 ng/ml KGF). Dose-response of KGF on HAECs was determined by morphological assessment; growth kinetic evaluation; immunocytochemical analysis; stemness and epithelial gene expression quantification with two step real time RT-PCR. KGF promotes the proliferation of HAECs with maximal effect observed at 10 ng/ml KGF. However, KGF decreased the stemness genes expression: Oct-3/4, Sox-2, Nanog3, Rex-1, FGF-4, FZD-9 and BST-1. KGF also down-regulates epithelial genes expression: CK3, CK18, CK19, Integrin-β1, p63 and involucrin in cultured HAECs. No significant difference on the gene expression was detected for each Nestin, ABCG-2, CK1 and CK14 in KGF-treated HAECs. Immunocytochemical analysis for both control and KGF-treated HAECs demonstrated positive staining against CK14 and CK18 but negative staining against involucrin. The results suggested that KGF stimulates an early differentiation of HAECs towards epidermal cells. Differentiation of KGF-treated HAECs to corneal lineage is unfavourable. Therefore, further studies are needed to elucidate the roles of KGF in the differentiation of HAECs towards skin keratinocytes.

Matched MeSH terms: Amnion/cytology*
Stemness and angiogenic gene expression changes of serial-passage human amnion mesenchymal cells

Fatimah SS, Tan GC, Chua K, Fariha MM, Tan AE, Hayati AR

Microvasc Res, 2013 Mar;86:21-9.
PMID: 23261754 DOI: 10.1016/j.mvr.2012.12.004

Particular attention has been directed towards human amnion mesenchymal stem cells (HAMCs) due to their accessibility, availability and immunomodulatory properties. Therefore, the aim of the present study was to determine the temporal changes of stemness and angiogenic gene expressions of serial-passage HAMCs.

Matched MeSH terms: Amnion/cytology*
Decellularization and genipin crosslinking of amniotic membrane suitable for tissue engineering applications

Gobinathan S, Zainol SS, Azizi SF, Iman NM, Muniandy R, Hasmad HN, et al.

J Biomater Sci Polym Ed, 2018 12;29(17):2051-2067.
PMID: 29983100 DOI: 10.1080/09205063.2018.1485814

Amniotic membrane has the potential to be used as scaffold in various tissue engineering applications. However, increasing its biostability at the same time maintaining its biocompatibility is important to enhance its usage as a scaffold. This studied characteristics genipin-crosslinked amniotic membrane as a bioscaffold. Redundant human amniotic membranes (HAM) divided into native (nAM), decellularized (dAM) and genipin-crosslinked (clAM) groups. The dAM and clAM group were decellularized using thermolysin (TL) and sodium hydroxide (NaOH) solution. Next, clAM group was crosslinked with 0.5% and 1.0% (w/v) genipin. The HAM was then studied for in vitro degradation, percentage of swelling, optical clarity, ultrastructure and mechanical strength. Meanwhile, fibroblasts isolated from nasal turbinates were then seeded onto nAM, dAM and clAM for biocompatibility studies. clAM had the slowest degradation rate and were still morphologically intact after 30 days of incubation in 0.01% collagenase type 1 solution. The dAM had a significantly highest percentage of swelling than other groups (p

Matched MeSH terms: Amnion/cytology; Amnion/chemistry*
Serial membrane sweeping at term in planned vaginal birth after cesarean: a randomized controlled trial

Hamdan M, Sidhu K, Sabir N, Omar SZ, Tan PC

Obstet Gynecol, 2009 Oct;114(4):745-751.
PMID: 19888030 DOI: 10.1097/AOG.0b013e3181b8fa00

OBJECTIVE: To estimate the effect of serial membrane sweeping on the onset of labor in women who planned vaginal birth after cesarean (VBAC).
METHODS: Women at term with one transverse lower segment cesarean delivery who were suitable for and who planned VBAC were approached to participate. Participants were randomly assigned to weekly membrane sweeping or weekly vaginal assessment for Bishop score until delivery. Participants and delivery providers were blinded to the allocated treatment. Standard obstetric care was given to all participants. The primary outcome was onset of labor which was defined as the presence of spontaneous regular and painful contractions that cause cervical dilation to at least 3 cm or prelabor rupture of membranes. Secondary outcomes included induction of labor and repeat cesarean delivery.
RESULTS: One hundred eight women were randomly assigned to membrane sweeping and 105 to control. The spontaneous labor rate was 78.5% compared with 72.1% (relative risk [RR] 1.1, 95% confidence interval [CI] 0.9-1.3; P=.34), the induction of labor rate was 12.1% compared with 9.6% (RR 1.3, 95% CI 0.6-2.8; P=.66), and the all-cause cesarean delivery rate was 40.2% compared with 44.2% (RR 0.9, 95% CI 0.7-1.2; P=.58) for the membrane sweeping and control groups, respectively. Gestational age at delivery (mean+/-standard deviation) of 39.6+/-1.0 weeks for the membrane sweeping group compared with 39.6+/-0.9 weeks for the control group (P=.84) was no different.
CONCLUSION: Serial membrane sweeping at term in women who planned VBAC has no significant effect on the onset of labor, pregnancy duration, induction of labor, or repeat cesarean delivery.
CLINICAL TRIAL REGISTRATION: ISRCTN, isrctn.org, ISRCTN55163179.
LEVEL OF EVIDENCE: I.

Matched MeSH terms: Amnion*
Fulltext Underlay myringoplasty: comparison of human amniotic membrane to temporalis fascia graft

Harvinder S, Hassan S, Sidek DS, Hamzah M, Samsudin AR, Philip R

Med J Malaysia, 2005 Dec;60(5):585-9.
PMID: 16515109

Human amniotic membrane as a homograft material was compared to temporalis fascia to close tympanic membrane perforations in 50 patients with chronic otitis media. Human amniotic membrane was used in 20 patients while temporalis fascia was used in the remaining 30. Anatomical closure of the perforation and reduction of the air-bone gap was measured. The graft uptake showed a 65% success rate for the amniotic membrane and 56.7% for the temporalis fascia at 3 months post-operatively. Significant closure of air-bone gap was observed in the human amniotic group. These results indicate comparable outcomes between human amniotic membrane and the temporalis fascia graft.

Matched MeSH terms: Amnion/transplantation*
Fulltext Angiogenic potential of extracellular matrix of human amniotic membrane

Hashim SNM, Yusof MFH, Zahari W, Noordin KBAA, Kannan TP, Hamid SSA, et al.

Tissue Eng Regen Med, 2016 Jun;13(3):211-217.
PMID: 30603401 DOI: 10.1007/s13770-016-9057-6

Combination between tissue engineering and other fields has brought an innovation in the area of regenerative medicine which ultimate aims are to repair, improve, and produce a good tissue construct. The availability of many types of scaffold, both synthetically and naturally have developed into many outstanding end products that have achieved the general objective in tissue engineering. Interestingly, most of this scaffold emulates extracellular matrix (ECM) characteristics. Therefore, ECM component sparks an interest to be explored and manipulated. The ECM featured in human amniotic membrane (HAM) provides a suitable niche for the cells to adhere, grow, proliferate, migrate and differentiate, and could possibly contribute to the production of angiogenic micro-environment indirectly. Previously, HAM scaffold has been widely used to accelerate wound healing, treat bone related and ocular diseases, and involved in cardiovascular repair. Also, it has been used in the angiogenicity study, but with a different technical approach. In addition, both side of HAM could be used in cellularised and decellularised conditions depending on the objectives of a particular research. Therefore, it is of paramount importance to investigate the behavior of ECM components especially on the stromal side of HAM and further explore the angiogenic potential exhibited by this scaffold.

Matched MeSH terms: Amnion
Human Amniotic Membrane with Aligned Electrospun Fiber as Scaffold for Aligned Tissue Regeneration

Hasmad H, Yusof MR, Mohd Razi ZR, Hj Idrus RB, Chowdhury SR

Tissue Eng Part C Methods, 2018 06;24(6):368-378.
PMID: 29690856 DOI: 10.1089/ten.TEC.2017.0447

Fabrication of composite scaffolds is one of the strategies proposed to enhance the functionality of tissue-engineered scaffolds for improved tissue regeneration. By combining multiple elements together, unique biomimetic scaffolds with desirable physical and mechanical properties can be tailored for tissue-specific applications. Despite having a highly porous structure, the utility of electrospun fibers (EF) as scaffold is usually hampered by their insufficient mechanical strength. In this study, we attempted to produce a mechanically competent scaffold with cell-guiding ability by fabricating aligned poly lactic-co-glycolic acid (PLGA) fibers on decellularized human amniotic membrane (HAM), known to possess favorable tensile and wound healing properties. Decellularization of HAM in 18.75 μg/mL of thermolysin followed by a brief treatment in 0.25 M sodium hydroxide efficiently removed the amniotic epithelium and preserved the ultrastructure of the underlying extracellular matrix. The electrospinning of 20% (w/v) PLGA 50:50 polymer on HAM yielded beadless fibers with straight morphology. Subsequent physical characterization revealed that EF-HAM scaffold with a 3-min fabrication had the most aligned fibers with the lowest fiber diameter in comparison with EF-HAM 5- and 7-min scaffolds. Hydrated EF-HAM scaffolds with 3-min deposition had a greater tensile strength than the other scaffolds despite having thinner fibers. Nevertheless, wet HAM and EF-HAMs regardless of the fiber thicknesses had a significantly lower Young's modulus, and hence, a higher elasticity compared with dry HAM and EF-HAMs. Biocompatibility analysis showed that the viability and migration rate of skeletal muscle cells on EF-HAMs were similar to control and HAM alone. Skeletal muscle cells seeded on HAM were shown to display random orientation, whereas cells on EF-HAM scaffolds were oriented along the alignment of the electrospun PLGA fibers. In summary, besides having good mechanical strength and elasticity, EF-HAM scaffold design decorated with aligned fiber topography holds a promising potential for use in the development of aligned tissue constructs.

Matched MeSH terms: Amnion/cytology*
Blood compatibility of human amniotic membrane compared with heparin-coated ePTFE for vascular tissue engineering

Kakavand M, Yazdanpanah G, Ahmadiani A, Niknejad H

J Tissue Eng Regen Med, 2017 06;11(6):1701-1709.
PMID: 26190586 DOI: 10.1002/term.2064

Amniotic membrane (AM), a placenta-derived natural biomaterial, has several characteristics which make it a potential substitute for blood vessels. However, there are no reports on the effects of the AM on blood components. The aim of this study was to evaluate the blood compatibility of the epithelial and mesenchymal surfaces of the amnion for potential use in vascular tissue engineering. The activation of intrinsic and extrinsic pathways of the clotting system, haemolysis and platelet adhesion were studied and the results were compared with heparin-coated expanded polytetrafluoroethylene (ePTFE) as a standard synthetic vascular graft. Prothrombin time (PT), activated partial thromboplastin time (aPTT), clotting time (CT) and haemolysis (%) tests showed that both the epithelial and mesenchymal sides of the AM are haemocompatible. Platelet aggregation and P-selectin production from the platelets showed that the epithelial surface of the AM has less induction of platelet activation than ePTFE. The results of scanning electron microscopy (SEM) demonstrated that platelets in contact with ePTFE had a higher rate of adhesion than with the epithelial and mesenchymal surfaces of the AM. Moreover, the morphological distribution of the platelets showed that the majority of platelets were round, while a large number of cells on ePTFE were dendritic. These results suggest that the AM which contains epithelial and mesenchymal stem cells has appropriate haemocompatibility to be employed in vascular tissue engineering, especially as a vein substitute. Copyright © 2015 John Wiley & Sons, Ltd.

Matched MeSH terms: Amnion/chemistry*
Fulltext Biocompatibility and toxicity of poly(vinyl alcohol)/N,O-carboxymethyl chitosan scaffold

Kamarul T, Krishnamurithy G, Salih ND, Ibrahim NS, Raghavendran HR, Suhaeb AR, et al.

ScientificWorldJournal, 2014;2014:905103.
PMID: 25298970 DOI: 10.1155/2014/905103

The in vivo biocompatibility and toxicity of PVA/NOCC scaffold were tested by comparing them with those of a biocompatible inert material HAM in a rat model. On Day 5, changes in the blood parameters of the PVA/NOCC-implanted rats were significantly higher than those of the control. The levels of potassium, creatinine, total protein, A/G, hemoglobulin, erythrocytes, WBC, and platelets were not significantly altered in the HAM-implanted rats, when compared with those in the control. On Day 10, an increase in potassium, urea, and GGT levels and a decrease in ALP, platelet, and eosinophil levels were noted in the PVA/NOCC-implanted rats, when compared with control. These changes were almost similar to those noted in the HAM-implanted rats, except for the unaltered potassium and increased neutrophil levels. On Day 15, the total protein, A/G, lymphocyte, monocyte, and eosinophil levels remained unaltered in the PVA/NOCC-implanted rats, whereas urea, A/G, WBC, lymphocyte, and monocyte levels remained unchanged in the HAM-implanted rats. Histology and immunohistochemistry analyses revealed inflammatory infiltration in the PVA/NOCC-implanted rats, but not in the HAM-implanted rats. Although a low toxic tissue response was observed in the PVA/NOCC-implanted rats, further studies are necessary to justify the use of this material in tissue engineering applications.

Matched MeSH terms: Amnion/metabolism
Fulltext Outcome of Various Pterygium Excision Techniques in Tertiary Ophthalmic Centre in East Coast Malaysia

Khairidzan, M.K., Fatimah, S.S., Thangasamy, V.K.

International Medical Journal Malaysia, 2006;5(1):1-2.
MyJurnal

Pterygium is a common external eye problem. It is more frequently seen in tropical areas regions where exposure to ultraviolet sunlight is high. Clinically, a pterygium is a wing shaped fibrovascular growth arising from the bulbar conjunctiva onto the superficial cornea. Complications of pterygium include decreased in visual acuity, dryness, foreign body sensation and persistent redness. Surgical management is the mainstay of treatment for this condition. Numerous surgical techniques have been described in the treatment of pterygium. They include the bare sclera technique, simple direct conjunctival closure, rotational conjunctival graft and conjunctival autograft. Additional treatment to some of these techniques may include the use of beta particle therapy and antimetabolite therapy. Despite the wide range of surgical procedures described for its treatment, the main concern from these procedures has been the recurrence, which could be as high as 30% to 70%. Recurrent pterygium is often accompanied by increased conjunctival inflammation and accelerated corneal involvement. Repeated surgical procedures often only worsen the situation, as loss of conjunctival tissue and scarring can result in obliteration of the fornices and mechanical restriction of extraocular movements, with clinically significant diplopia. In Hospital Tengku Ampuan Afzan, pterygium excision is the most common surgical procedure after cataract extraction. We reviewed patients who had undergone pterygium surgery in HTAA in order to determine the most effective surgical method that could minimize recurrence. PURPOSE: To compare success rates of various excision techniques performed for primary and recurrent pterygium in Hospital Tengku Ampuan Afzan, Kuantan, Pahang.
METHODS: The outcome of 47 cases of pterygia (44 primary and 3 recurrent) excised with various techniques between January 2004 to September 2004 was retrospectively reviewed. Six clinical specialists and four trainees performed the surgical procedures. Outcome was evaluated in terms of recurrence of pterygia onto the cornea. RESULTS: The mean follow up was 3.04 months (range, 1-7 months). All pterygia were morphologically graded as intermediate or fleshy type except one. Four types of pterygium excision techniques were performed. Twenty-four cases had bare sclera, seventeen cases had conjunctival autograft transplantation, six cases had direct conjunctival closure and one had amniotic membrane transplantation done. Recurrence of pterygia occurred in thirteen eyes. Twelve cases from primary pterygia group and one case from recurrent group recurred. Recurrence rate was noted to be higher in direct conjunctival closure (4 out of 6 cases) and lowest in conjunctival autograft transplantation (2 out of 17 cases). Recurrence rate for bare sclera technique was noted to rank second in this study (6 out of 24 cases). In five cases of recurrence, subconjunctival tissue invasions were more than 1 mm but further surgical interventions were not needed at the time of this review was done. CONCLUSIONS: Conjunctival autografting was found to have less recurrent rate when compared with other techniques. The bare sclera technique was quoted to be associated with higher recurrence rate in other literatures. Interestingly in our series, recurrence rate for direct conjunctival closure technique was higher when compared to the former technique. This may be related to inadequate excision of pterygia tissue, which led to direct apposition of abnormal tissue to the cornea in the direct conjunctival closure technique. Even though the bare sclera technique is associated with a higher recurrence rate, it is still the preferred excision technique. This could be because it is less time consuming and technically easier to perform. Based on this study, conjunctival autografting should be the surgical procedure of choice for pteryigum in order to minimise the risk of recurrence.

Matched MeSH terms: Amnion
Fulltext Fracture toughness of human amniotic membranes

Koh CT, Tonsomboon K, Oyen ML

Interface Focus, 2019 Oct 06;9(5):20190012.
PMID: 31485308 DOI: 10.1098/rsfs.2019.0012

Amnion is a membrane that surrounds and structurally protects the developing fetus during pregnancy. The rupture of amniotic membranes prior to both normal and preterm deliveries involves stretch forces acting on a biochemically triggered weak zone of the membranes. Fracture toughness is an important mechanical property describing how the membranes containing a defect resist fracture, but this property has never been investigated in amniotic membranes. In this work, the fracture toughness of many samples cut from four pieces of amniotic membrane from different mothers was examined by uniaxial and pure shear (mode I) fracture tests. The measurement was checked for dependence on the sample geometry and notch length. Results from the uniaxial tensile test show J-shaped stress-strain curves and confirm that the amniotic membrane is a nonlinear material. The measured fracture toughness of four amniotic membranes ranged from 0.96 ± 0.11 to 1.83 ± 0.18 kJ m-2. Despite considering the effect of the presence of the defect on mechanical property measurement, similar fracture behaviour was observed for pre-notched and unnotched specimens, indicating that the membranes were extremely tolerant to defects. This defect-tolerant characteristic provides insight into the understanding of fetal membrane rupture.

Matched MeSH terms: Amnion
Human amniotic membrane as a chondrocyte carrier vehicle/substrate: in vitro study

Krishnamurithy G, Shilpa PN, Ahmad RE, Sulaiman S, Ng CL, Kamarul T

J Biomed Mater Res A, 2011 Dec 01;99(3):500-6.
PMID: 21913317 DOI: 10.1002/jbm.a.33184

Human amniotic membrane (HAM) is an established biomaterial used in many clinical applications. However, its use for tissue engineering purposes has not been fully realized. A study was therefore conducted to evaluate the feasibility of using HAM as a chondrocyte substrate/carrier. HAMs were obtained from fresh human placenta and were process to produced air dried HAM (AdHAM) and freeze dried HAM (FdHAM). Rabbit chondrocytes were isolated and expanded in vitro and seeded onto these preparations. Cell proliferation, GAG expression and GAG/cell expression were measured at days 3, 6, 9, 12, 15, 21, and 28. These were compared to chondrocytes seeded onto plastic surfaces. Histological analysis and scanning electron microscopy was performed to observe cell attachment. There was significantly higher cell proliferation rates observed between AdHAM (13-51%, P=0.001) or FdHAM (18-48%, p = 0.001) to chondrocytes in monolayer. Similarly, GAG and GAG/cell expressed in AdHAM (33-82%, p = 0.001; 22-60%, p = 0.001) or FdHAM (41-81%, p = 0.001: 28-60%, p = 0.001) were significantly higher than monolayer cultures. However, no significant differences were observed in the proliferation rates (p = 0.576), GAG expression (p = 0.476) and GAG/cell expression (p = 0.135) between AdHAM and FdHAM. The histology and scanning electron microscopy assessments demonstrates good chondrocyte attachments on both HAMs. In conclusion, both AdHAM and FdHAM provide superior chondrocyte proliferation, GAG expression, and attachment than monolayer cultures making it a potential substrate/carrier for cell based cartilage therapy and transplantation.

Matched MeSH terms: Amnion/metabolism*; Amnion/ultrastructure

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