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Abstract

Hydrogels, due to their hygroscopic nature, have been widely used as wound dressings, and their resemblance to native extracellular matrix (ECM) has lead to the recreation of three-dimensional ECM-like microenvironments. Overall, hydrogels show limited molecular diffusion and cell binding sites. Gellan gum-based spongy-like hydrogels, produced by a sequential advanced processing methodology, reunite hydrogels benefits and the additional capacity to control specific cell behavior. These structures can be stored as dried networks that after rehydration with a solution containing bioactive molecules and/or cells form spongy-like hydrogels. They show physical stability, flexibility, and viscoelasticity and facilitated manipulation for bioactive molecules and/or cells incorporation, in comparison to traditional hydrogels. These characteristics make them attractive for skin regeneration purposes. Herein we present the work leading to spongy-like hydrogels, highlighting the possibility of fine-tuning their properties, and effects of incorporating hyaluronic acid, adult skin cells, and stem cells to meet the demands of specific wound types.
... Porous 3D hydrogel calcium alginate (Ca ALG) has great swelling capacity in wounds, providing slow drug release, and it is used to entrap cells for tissue regeneration and engineering, as a physical support for cells or tissue or as a hurdle between two media, because it protects the cells from the host's immune system until it reaches the targeted area. A great example is represented by the encapsulated fibroblasts into a duallayered structure made from alginate hydrogel with apical keratinocytes [32,58,59]. Also, a hydrogel film based on poly (N-vinyl caprolactam)-calcium alginate (PVCL/PV-Ca ALG) loaded with thrombin receptor agonist peptide (TRAP) has shown a beneficial effect on wound healing and tissue regeneration [11]. ...
... The ACF-HS treated wounds displayed better Porous 3D hydrogel calcium alginate (Ca ALG) has great swelling capacity in wounds, providing slow drug release, and it is used to entrap cells for tissue regeneration and engineering, as a physical support for cells or tissue or as a hurdle between two media, because it protects the cells from the host's immune system until it reaches the targeted area. A great example is represented by the encapsulated fibroblasts into a dual-layered structure made from alginate hydrogel with apical keratinocytes [32,58,59]. Also, a hydrogel film based on poly (N-vinyl caprolactam)-calcium alginate (PVCL/PV-Ca ALG) loaded with thrombin receptor agonist peptide (TRAP) has shown a beneficial effect on wound healing and tissue regeneration [11]. ...
Article
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Chronic wounds represent a major public health issue, with an extremely high cost worldwide. In healthy individuals, the wound healing process takes place in different stages: inflammation, cell proliferation (fibroblasts and keratinocytes of the dermis), and finally remodeling of the extracellular matrix (equilibrium between metalloproteinases and their inhibitors). In chronic wounds, the chronic inflammation favors exudate persistence and bacterial film has a special importance in the dynamics of chronic inflammation in wounds that do not heal. Recent advances in biopolymer-based materials for wound healing highlight the performance of specific alginate forms. An ideal wound dressing should be adherent to the wound surface and not to the wound bed, it should also be non-antigenic, biocompatible, semi-permeable, biodegradable, elastic but resistant, and cost-effective. It has to give protection against bacterial, infectious, mechanical, and thermal agents, to modulate the level of wound moisture, and to entrap and deliver drugs or other molecules This paper explores the roles of alginates in advanced wound-dressing forms with a particular emphasis on hydrogels, nanofibers networks, 3D-scaffolds or sponges entrapping fibroblasts, keratinocytes, or drugs to be released on the wound-bed. The latest research reports are presented and supported with in vitro and in vivo studies from the current literature.
... Hydrogels are very useful in this aspect considering that they increase the residual time for the stem cells in the wound (Natesan et al., 2013;Xu et al., 2013;Garg et al., 2014;Chen et al., 2015;Kosaraju et al., 2016;Cheng et al., 2017;da Silva et al., 2017;Kaisang et al., 2017;Dong et al., 2018;Lei et al., 2018;Shou et al., 2018;Xu et al., 2018;Hsu et al., 2019). In general, this is possible due to hydrogels being the promoter of the cell adhesion and acting as a medium for maintaining the proper phenotype of the cells (Seliktar, 2012;Rice et al., 2013;da Silva et al., 2016). This homing property is improved by pre-culturing the stem cells in hydrogels in vitro, as some studies have shown extended period of cell dwelling time in the wound up to 11 days post transplantation (Rustad et al., 2012;Zeng et al., 2015). ...
Article
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Wound healing is a common physiological process which consists of a sequence of molecular and cellular events that occur following the onset of a tissue lesion in order to reconstitute barrier between body and external environment. The inherent properties of hydrogels allow the damaged tissue to heal by supporting a hydrated environment which has long been explored in wound management to aid in autolytic debridement. However, chronic non-healing wounds require added therapeutic features that can be achieved by incorporation of biomolecules and supporting cells to promote faster and better healing outcomes. In recent decades, numerous hydrogels have been developed and modified to match the time scale for distinct stages of wound healing. This review will discuss the effects of various types of hydrogels on wound pathophysiology, as well as the ideal characteristics of hydrogels for wound healing, crosslinking mechanism, fabrication techniques and design considerations of hydrogel engineering. Finally, several challenges related to adopting hydrogels to promote wound healing and future perspectives are discussed.
... Hydrogels are 3D porous hydrophilic polymeric networks, containing high amount of water that mimics the natural tissue [4]. Owing to their biocompatibility, flexibility, and elasticity, hydrogels are used for wound dressing [5,6]. ...
Article
Hydrogels are excellent wound healing materials. However, due to the wear and tear at the wound site, the hydrogels can lose their structural and functional integrity. To overcome this and to effectively seal the wound and control infection, an in-situ silver nanoparticles (AgNps) incorporated N, O-carboxymethyl chitosan (N, O-CMC) based self-healing hydrogel using ethylenediaminetetraacetic acid-ferric ion (EDTA: Fe³⁺) complex was developed. The prepared N, O-CMC/AgNps hydrogel was characterized using FTIR, SEM, and TEM. The developed N, O-CMC/AgNps hydrogel was found to be adhesive, injectable, conductive, bio-compatible, and showed antibacterial activity against ATCC and clinical strains of E. coli, K. pneumonia, P. aeruginosa, S. aureus and MRSA. N, O-CMC/AgNps hydrogel also showed anti-biofilm activity against S. aureus, E. coli, and P. aeruginosa (ATCC strains). This developed antibacterial and self-healing N, O-CMC/AgNps hydrogel can be used in the treatment of infected wounds.
... There is a wide body of existing literature that evidences the benefits of using hydrogels in wound dressings [54][55][56][57]. In particular, absorbent systems like alginate are cited for their promising absorption capabilities of up to 20 times their weight in fluid making them useful for treating infected wounds [58]. ...
Article
The enzymatic oxidation of glucose to produce reactive oxygen species (ROS) provides honey with antimicrobial efficacy. This mechanism offers an alternative to traditional antibiotics; however, topical use of honey is limited due to its adherent and highly viscous properties. This study aims to overcome these issues by engineering a powder-based system that eases delivery and offers in situ activation of ROS. Starch based drying agents were utilised to enable freeze drying of a medical honey, with methylated-β-cyclodextrin (MCD) enabling the highest active incorporation (70%) while still producing a free-flowing powder. Addition of a superabsorbent, sodium polyacrylate (≤40%) was shown to facilitate in situ gelation of the powder, with an absorption capacity of up to 120.7 ± 4.5 mL g−1. Promisingly efficacy of the optimised superabsorbent powder was demonstrated in vitro against several clinically relevant Gram-negative and Gram–positive bacteria (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa). Alongside this no adverse effects were observed against human dermal fibroblasts. Application of the superabsorbent powder in an ex-vivo porcine wound model revealed capability to form a protective hydrogel barrier in less than 1 min. Overall, this novel ROS producing superabsorbent powder has potential to tackle topical infections without using traditional antibiotics.
... Glycerol addition might also increase an alginates' film water solubility, swelling degree, and flexibility but it will decrease its mechanical stability. Also, the mechanical properties, solubility and swelling were within the accepted range if 10% glycerol was added to alginatepectin composite films, while the addition of glycerol to pullulanalginate films made them less resistant to tensile stress, more soluble in water, and their elongation at break value increased (DA SILVA & al [32]; VENUGOPAL [33]; DA SILVA & al [34]). For example, an ALG-Aloe vera film, obtained through the solvent-casting method and CaCl2 cross-linking, was thicker (66.14 µ m -75% ALG vs. 69.00 ...
Article
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Wound healing management is one of the most expensive and most common procedures in modern hospitals worldwide. The modern trend in wound healing is using bioactive compounds, either by themselves or in a blended form that enhances their advantages in order to ensure a fast and possibly scar-free healing. One of these biomaterials is alginate, a heteroglycan with anti-inflammatory, anti-microbial, anti-oxidant and hemostasis-induction properties, being capable to entrap drugs, proteins or growth factors that help wound healing. After a rigorous search of the findings made after 2013, we included the in vitro and in vivo studies that used alginate films and membranes, as well as the physicochemical differences between them, providing new perspectives on using different compositions when creating a material that could enhance the wound healing process. Keywords Alginate, biomaterial, dressing, in vitro studies, in vivo studies, wound healing. To cite this article: BARBU A, NEAMȚU MB, ZĂHAN M, MIREȘAN V. Trends in alginate-based films and membranes for wound healing. Rom Biotechnol Lett. 2020; 25(4): 1683-1689. DOI: 10.25083/rbl/25.4/1683.1689
... A thicker epidermis was evident when wounds were treated solely with the materials [40,45,55,85,86] in relation to the controls (sham), based on the rate of wound closure. This is consistent with the ability of these materials to promote the adhesion of KCs and hence function as a support for KCs, as observed for hyaluronic acid-based spongy-like hydrogels [85,[87][88][89] and collagen [40,55] or collagen-derived gelatin [45] structures that contain cell adhesive motifs. Nonetheless, a thicker epidermis was also found in wounds treated with tissue engineered constructs in relation to the control (materials) [40,55,61,72,85,86,90], which suggests and supports the hypothesis of a paracrine effect of the transplanted cells over re-epithelialization as described before. ...
Chapter
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This chapter focuses on the tissue engineering approaches that have been developed for the treatment of skin wounds with the aim of promoting cutaneous regeneration. It aims at revising and describing published work in skin tissue engineering with a focus on the most critical aspects of cutaneous wound healing, such as inflammation, re‐epithelialization, matrix synthesis and remodeling, vascularization, and the generation of skin adnexal features. Tissue engineered skin substitutes are among the most promising therapeutic options for those wounds not amenable to primary closure. Along with active progress in the field, skin tissue engineering strategies have focused on exploring different tools to attain the complexity of skin tissue. Although the majority of commercialized skin tissue engineered constructs use keratinocytes and fibroblasts, a wide number of studies have included other relevant cell types such as endothelial cells.
... Hydrogels are an excellent option as delivery vehicles, as they increase of the length of time that stem cells reside in a wound ( Table 2) (48, [103][104][105][106][107][108][109][110][111][112][113][114][115]. This property arises from the ability of some hydrogels to promote cell adhesion and to empower stem cell function by supporting the maintenance of their normal phenotype (23,116,117). These features are reinforced by in vitro preculture of stem cells within hydrogels, as demonstrated by the presence of transplanted cells in the wound for periods longer than 11 days post transplantation (Figure 4) (118, 119). ...
Article
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Chronic skin wounds are the leading cause of nontraumatic foot amputations worldwide and present a significant risk of morbidity and mortality due to the lack of efficient therapies. The intrinsic characteristics of hydrogels allow them to benefit cutaneous healing essentially by supporting a moist environment. This property has long been explored in wound management to aid in autolytic debridement. However, chronic wounds require additional therapeutic features that can be provided by a combination of hydrogels with biochemical mediators or cells, promoting faster and better healing. We survey hydrogel-based approaches with potential to improve the healing of chronic wounds by reviewing their effects as observed in preclinical models. Topics covered include strategies to ablate infection and resolve inflammation, the delivery of bioactive agents to accelerate healing, and tissue engineering approaches for skin regeneration. The article concludes by considering the relevance of treating chronic skin wounds using hydrogel-based strategies.
Article
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Non-functional skin tissue has been the most common outcome of the healing of wounds treated with the currently available substitutes. Thus, urgent care is needed to promote an effective and complete regeneration. To meet this, we proposed the assembling of a construct that take advantage of cell-adhesive gellan gum-hyaluronic acid (GG-HA) spongy-like hydrogels and a powerful cell-machinery obtained from adipose tissue, human adipose stem cells (hASCs) and microvascular endothelial cells (hAMECs). In addition to a cell-adhesive character, GG-HA spongy-like hydrogels overpass limitations of traditional hydrogels, such as reduced physical stability and limited manipulation, due to improved microstructural arrangement and ameliorated mechanical performance. The pruposed constructs combining cellular mediators of the healing process within the spongy-like hydrogels that intend to recapitulate skin matrix, aim to promote neoskin vascularization. Stable and off-the-shelf dried GG-HA polymeric networks, rapidly re-hydrated at the time of cell seeding, then depicting features of both sponges and hydrogels, enabled the natural cell entrapment/encapsulation and consequent attachment and cell-polymer interactions. Upon transplantation into mice full-thickness excisional wounds, GG-HA spongy-like hydrogels absorbed the early inflammatory cell infiltrate and lead to the formation of a dense granulation tissue. Consequently, spongy-like hydrogel degradation was observed and progressive wound closure, re-epithelialization and matrix remodel was improved in relation to control condition. More importantly, GG-HA spongy-like hydrogels promoted a superior neovascularization, which was enhanced in the presence of human hAMECs, also found incorporated in the formed neovessels. These observations highlight the successful integration of a valuable matrix and pre-vascularization cues to target angiogenesis/neovascularization in skin full-thickness excisional wounds.
Article
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Cultivation and proliferation of stem cells in three-dimensional (3-D) scaffolds is a promising strategy for regenerative medicine. Mesenchymal stem cells with their potential to differentiate in various cell types, cryopreserved adhesion-based in fabricated scaffolds of biocompatible materials can serve as ready-to-use transplantation units for tissue repair, where pores allow a direct contact of graft cells and recipient tissue without further preparation. A successful cryopreservation of adherent cells depends on attachment and spreading processes that start directly after cell seeding. Here, we analyzed different cultivation times (0.5, 2, 24 h) prior to adhesion-based cryopreservation of human mesenchymal stem cells within alginate-gelatin cryogel scaffolds and its influence on cell viability, recovery and functionality at recovery times (0, 24, 48 h) in comparison to non-frozen control. Analysis with confocal laser scanning microscopy and scanning electron microscopy indicated that 2 h cultivation time enhanced cryopreservation success: cell number, visual cell contacts, membrane integrity, motility, as well as spreading were comparable to control. In contrast, cell number by short cultivation time (0.5 h) reduced dramatically after thawing and expanded cultivation time (24 h) decreased cell viability. Our results provide necessary information to enhance the production and to store ready-to-use transplantation units for application in bone, cartilage or skin regenerative therapy.
Article
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Introduction Cell therapy using adipose-derived stem cells has been reported to improve chronic wounds via differentiation and paracrine effects. One such strategy is to deliver stem cells in hydrogels, which are studied increasingly as cell delivery vehicles for therapeutic healing and inducing tissue regeneration. This study aimed to determine the behaviour of encapsulated adipose-derived stem cells and identify the secretion profile of suitable growth factors for wound healing in a newly developed thermoresponsive PEG–hyaluronic acid (HA) hybrid hydrogel to provide a novel living dressing system. Methods In this study, human adipose-derived stem cells (hADSCs) were encapsulated in situ in a water-soluble, thermoresponsive hyperbranched PEG-based copolymer (PEGMEMA–MEO2MA–PEGDA) with multiple acrylate functional groups in combination with thiolated HA, which was developed via deactivated enhanced atom transfer radical polymerisation of poly(ethylene glycol) methyl ether methacrylate (PEGMEMA, Mn = 475), 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and poly(ethylene glycol) diacrylate PEGDA (Mn = 258). hADSCs embedded in the PEGMEMA–MEO2MA–PEGDA and HA hybrid hydrogel system (P-SH-HA) were monitored and analysed for their cell viability, cell proliferation and secretion of growth factors (vascular endothelial growth factor, transforming growth factor beta and placental-derived growth factor) and cytokines (IFNγ, IL-2 and IL-10) under three-dimensional culture conditions via the ATP activity assay, alamarBlue® assay, LIVE/DEAD® assay and multiplex ELISA, respectively. Results hADSCs were successfully encapsulated in situ with high cell viability for up to 7 days in hydrogels. Although cellular proliferation was inhibited, cellular secretion of growth factors such as vascular endothelial growth factor and placental-derived growth factor production increased over 7 days, whereas IL-2 and IFNγ release were unaffected. Conclusion This study indicates that hADSCs can be maintained in a P-SH-HA hydrogel, and secrete pro-angiogenic growth factors with low cytotoxicity. With the potential to add more functionality for further structural modifications, this stem cell hydrogel system can be an ideal living dressing system for wound healing applications.
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The aim of the current research work was to prepare and evaluate different generations of superporous hydrogels (SPH) of acrylamide and chitosan using gas blowing technique and evaluate them for swelling, mechanical properties, FTIR, SEM, XRD, and in vitro drug release. The ingredients used were acrylamide, N,N′-methylene bisacrylamide, chitosan, Pluronic F127, ammonium per sulfate-N,N,N′,N′-tetramethylenediamine, and sodium bicarbonate. All ingredients were mixed sequentially with thorough stirring. The effect of different drying conditions on properties of SPH was also evaluated. Ethanol treated batched showed maximum swelling properties due to uniform pores as indicated in SEM studies. Equilibrium swelling time was less than 10 min in all batches. Freeze drying led to lowering of density which is also supported by porosity and void fraction data. Maximum mechanical strength was found in superporous hydrogel interpenetrating networks due to crosslinked polymeric network. 70% drug was released at the end of 2 h, and further the release was sustained till the end of 24 h. In vitro drug release kinetics showed that drug release occurs by diffusion and follows Super Case II transport indicating that mechanism of drug release is not clear. Superporous hydrogel interpenetrating networks can be successfully used as sustained release gastroretentive devices.
Book
Despite their capacity to carry out functions that previously were unobtainable, smart polymers and hydrogels tend to have painfully slow response times. On the other hand biological systems go through phase changes at an extremely fast rate. Reflexive Polymers and Hydrogels examines the natural systems that respond almost instantaneously to environmental stimuli, and thus gives the reader an understanding of the mechanisms that govern these responses. The book includes chapters on approaches and procedures for designing a synthetic …flash… system based on naturally occurring systems. It also deals with some of the promising potential applications of flash systems in industry.
Chapter
Injectable hydrogels can be used for wounds of any size, shape, or depth. They form a three-dimensional water-containing polymer network via physical or chemical cross-linking in situ. Because injectable hydrogels mimic the mechanical, swelling and shrinking properties of the native tissue, they have received increased attention in the fields of wound healing and tissue engineering. This chapter briefly summarizes the different types of injectable hydrogels and their applications in tissue engineering. A novel poly(ethylene glycol)-hyaluronic acid injectable hydrogel wound dressing is highlighted. The feasibility of combining this in situ–formed bioactive hydrogel dressing with adipose tissue–derived stem cells is demonstrated, showing its potential for clinical wound healing applications.
Article
The present manuscript reports the characterization, optimization of rheological properties, loading and release capabilities of 5'-GMP mediated β-FeOOH hydrogel. CD analysis indicates it to contain mainly the left handed helix similar to that of Z-DNA. The highest viscosity (> 300 cP) corresponds to the sample containing 2.5 × 10-3 mol dm-3 of 5'-GMP (SP2H). FESEM and TEM studies indicate the freeze dried (FD) SP2H to be porous in nature, which is also supported by its high BET surface area of 226 m2/g as compared to that of SP3H (75 m2/g). Selected area electron diffraction (SAED) analysis and Raman spectroscopy show it to contain β-FeOOH phase. The FD SP2H exhibits the high swelling ratio (326%) and loading capacity for methylene blue (MB) dye. It displays a controlled and efficient release (> 90%) for optimized [MB] (2.5 × 10-4 mol dm-3) in 48 h. The low toxicity of as synthesized FD-SP2H nanostructures against MDA-MB-231 (breast cancer cells) up to 100 μg /mL suggests its biocompatible nature. The high porosity, surface area, % swelling, loading and release performance of the hydrogel indicate its potential for the drug delivery and other biological applications.
Article
Superporous poly(2-hydroxyethyl methacrylate) (PHEMA) is successfully used as a scaffold material for tissue engineering; however, it lacks functional groups that support cell adhesion. The objective of this study was to investigate the cell-adhesive properties of biomimetic ligands, such as laminin-derived Ac-CGGASIKVAVS-OH (SIKVAV) peptide and fibronectin subunits (Fn), as well as small molecules exemplified by 2-mercaptoethanol (ME) and cysteine (Cys), immobilized on a copolymer of 2-hydroxyethyl methacrylate (HEMA) with 2-aminoethyl methacrylate (AEMA) by a maleimide-thiol coupling reaction. The maleimide group was introduced to the P(HEMA-AEMA) hydrogels by the reaction of their amino groups with N-γ-maleimidobutyryl-oxysuccinimide ester (GMBS). Mesenchymal stem cells (MSCs) were used to investigate the cell adhesive properties of the modified hydrogels. A significantly larger area of cell growth as well as a higher cell density were found on Fn- and SIKVAV-modified hydrogels when compared to the ME- and Cys-modified supports or neat P(HEMA-AEMA). Moreover, Fn-modification strongly stimulated cell proliferation. The ability of MSCs to differentiate into adipocytes and osteoblasts was maintained on both Fn- and SIKVAV-modifications, but it was reduced on ME-modified hydrogels and neat P(HEMA-AEMA). The results show that the immobilization of SIKVAV and Fn-subunits onto superporous P(HEMA-AEMA) hydrogels via a GMBS coupling reaction improves cell adhesive properties. The high proliferative activity observed on Fn-modified hydrogels suggests that the immobilized Fn-subunits maintain their bioactivity and thus represent a promising tool for application in tissue engineering.
Article
In this study, porous three-dimensional hydrogel matrices are fabricated composed of silk cocoon protein sericin of non-mulberry silkworm Antheraea mylitta and carboxymethyl cellulose. The matrices are prepared via freeze-drying technique followed by dual crosslinking with glutaraldehyde and aluminum chloride. The microstructure of the hydrogel matrices are assessed using scanning electron microscopy and biophysical characterization are carried out using FTIR and XRD. The TGF-β1 release from the crosslinked matrices as a growth factor is evaluated by immunosorbent assay. Live dead assay and MTT assay shows no cytotoxicity of blended matrices towards human keratinocytes. The matrices support the cell attachment and proliferation of human keratinocytes as observed through SEM and confocal images. Gelatin zymography demonstrates the low levels of MMP-2 and insignificant amount of MMP-9 in the culture media of cell seeded matrices. Low inflammatory response of the matrices is indicated through TNF-α release assay. The results indicate that the fabricated matrices constitute three-dimensional cell-interactive environment for tissue engineering applications and its potential use as a future cellular biological wound dressing material.
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Three-dimensional (3D) growth of cell is of particular interest in the field of tissue engineering and regenerative medicine. Scaffolds used for this purpose are often tailor-made to mimic the microenvironment and the extracellular matrix of the tissue with defined role such as to provide appropriate structural, chemical, and mechanical support. The aim of the study was to design the macroporous matrix with potential in the field of tissue engineering especially for lung muscle regeneration. Blend of hydroxyethyl methacrylate-alginate-gelatin (HAG) cryogel scaffold was synthesized using cryogelation technique and this polymer material combination is being reported first time. The rheology study showed the elastic property of the material in wet state with no variation in storage modulus (G'), loss modulus (G″), and phase angle upon temperature variation. The microcomputer tomography (micro-CT) analysis confirmed the homogenous polymer structure with average pore diameter of 84 μm. Scaffold synthesized using polymer combinations which is mixture of polysaccharide (alginate) and protein (gelatin) provides supportive environment for human lung epithelial cell proliferation confirmed by cytoskeletal stain phalloidin and nuclei staining 4',6-diamidino-2-phenylindole checked for over three weeks. The in vivo biocompatibility was further performed which showed integration of scaffold to the surrounding tissue with ability to recruit cells. However, at first week, small amount of infiltrating mast cells were found which subsequently diminished in following weeks. Immunohistochemistry for dendritic cells confirmed in vivo biocompatible nature of the HAG scaffold. The mechanical strength, stiffness, elastic measurements, in vivo compatibility, and in vitro lung cell proliferation show the potentiality of HAG materials for lung tissue engineering.