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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Bioeng. Biotechnol.</journal-id>
<journal-title>Frontiers in Bioengineering and Biotechnology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Bioeng. Biotechnol.</abbrev-journal-title>
<issn pub-type="epub">2296-4185</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="publisher-id">731119</article-id>
<article-id pub-id-type="doi">10.3389/fbioe.2021.731119</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Bioengineering and Biotechnology</subject>
<subj-group>
<subject>Editorial</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Editorial: Advances in the Understanding of Tumor Microenvironment: Molecular and Theranostic Imaging</article-title>
<alt-title alt-title-type="left-running-head">Wang et&#x20;al.</alt-title>
<alt-title alt-title-type="right-running-head">Editorial: Tumor Microenvironment Imaging</alt-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Wang</surname>
<given-names>Shouju</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
<uri xlink:href="https://loop.frontiersin.org/people/939019/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Mao</surname>
<given-names>Hui</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/698641/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Cheng</surname>
<given-names>Zhen</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/93140/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Teng</surname>
<given-names>Zhaogang</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/939338/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Sun</surname>
<given-names>Xiaolian</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/939081/overview"/>
</contrib>
</contrib-group>
<aff id="aff1">
<label>
<sup>1</sup>
</label>Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, <addr-line>Nanjing</addr-line>, <country>China</country>
</aff>
<aff id="aff2">
<label>
<sup>2</sup>
</label>Department of Radiology and Imaging Sciences, Emory University School of Medicine, <addr-line>Atlanta</addr-line>, <addr-line>GA</addr-line>, <country>United&#x20;States</country>
</aff>
<aff id="aff3">
<label>
<sup>3</sup>
</label>Molecular Imaging Program at Stanford, Department of Radiology and Bio-X Program, Canary Center at Stanford for Cancer Early Detection, Stanford University, <addr-line>Stanford</addr-line>, <addr-line>CA</addr-line>, <country>United&#x20;States</country>
</aff>
<aff id="aff4">
<label>
<sup>4</sup>
</label>Key Laboratory for Organic Electronics and Information Displays, Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials, Jiangsu National Synergetic Innovation Centre for Advanced Materials, Nanjing University of Posts and Telecommunications, <addr-line>Nanjing</addr-line>, <country>China</country>
</aff>
<aff id="aff5">
<label>
<sup>5</sup>
</label>State Key Laboratory of Natural Medicines, Key Laboratory of Drug Quality Control and Pharmacovigilance, Department of Pharmaceutical Analysis, China Pharmaceutical University, <addr-line>Nanjing</addr-line>, <country>China</country>
</aff>
<author-notes>
<fn fn-type="edited-by">
<p>
<bold>Edited and Reviewed by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/120336/overview">Hasan Uludag</ext-link>, University of Alberta, Canada</p>
</fn>
<corresp id="c001">&#x2a;Correspondence: Shouju Wang, <email>shouju.wang@gmail.com</email>
</corresp>
<fn fn-type="other">
<p>This article was submitted to Biomaterials, a section of the journal Frontiers in Bioengineering and Biotechnology</p>
</fn>
</author-notes>
<pub-date pub-type="epub">
<day>05</day>
<month>08</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="collection">
<year>2021</year>
</pub-date>
<volume>9</volume>
<elocation-id>731119</elocation-id>
<history>
<date date-type="received">
<day>26</day>
<month>06</month>
<year>2021</year>
</date>
<date date-type="accepted">
<day>26</day>
<month>07</month>
<year>2021</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2021 Wang, Mao, Cheng, Teng and Sun.</copyright-statement>
<copyright-year>2021</copyright-year>
<copyright-holder>Wang, Mao, Cheng, Teng and Sun</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these&#x20;terms.</p>
</license>
</permissions>
<related-article id="RA1" related-article-type="commentary-article" xlink:href="https://www.frontiersin.org/researchtopic/13692" ext-link-type="uri">Editorial on the Research Topic<article-title>Advances in the Understanding of Tumor Microenvironment: Molecular and Theranostic Imaging</article-title>
</related-article>
<kwd-group>
<kwd>tumour microenvironment</kwd>
<kwd>molecular imaging</kwd>
<kwd>theranostics</kwd>
<kwd>immune microenvironment</kwd>
<kwd>nanoprobes</kwd>
</kwd-group>
</article-meta>
</front>
<body>
<p>Tumor microenvironment (TME) plays key roles in cancer development, prognosis and responses to treatments. However, given its heterogeneity and complex interactions/interplays with other malignant processes, investigating TME requires systematical and preferably non-disruptive approaches. Molecular imaging enables visualizing, characterizing, and even quantitatively measuring specific biological and molecular processes <italic>in vivo</italic> to monitor the heterogeneity and evolution of TME. Theranostic imaging, as a rapidly expanding facet of molecular imaging, also creates new possibilities to deploy treatment options targeting TME by delivering therapeutic agents or disruptive photothermal and photodynamic energy. The advanced molecular and theranostic imaging tools and approaches presented in this special issue, including one review article, one mini review article, and two original research articles, offer an overview and a few examples of such applications.</p>
<p>Focusing on immune therapy that aims to reverse the immune-suppressive TME, <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fbioe.2021.680315/full">Li et&#x20;al.</ext-link> provided a latest overview of the recent progress of breast cancer treatments, including the predictive biomarkers, immune checkpoint blockades, cancer vaccines, and adoptive cell therapy, which directly or indirectly changed TME to exert the efficacy. In this mini review article, the authors highlighted the potential of nanotechnology to monitor and control the tumor immune microenvironment. <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fbioe.2021.647905/full">Gao et&#x20;al.</ext-link> introduced the therapeutic applications of gold nanoparticles in cancer treatment and discussed the potential of using stimuli-responsive strategies to respond to TME and to increase the transport efficacy. Serval unique properties, such as localized surface plasma resonance and stimuli-responsive properties to hypoxia and acidic pH, making gold nanoparticles promising for transport therapeutic drugs to TME. In a research report, <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fbioe.2021.644648/full">Heaster et&#x20;al.</ext-link> demonstrated intravital metabolic autofluorescence imaging can be used to resolve the dynamic macrophage function and reveal the heterogeneity of macrophage between normal and cancerous microenvironments <italic>in vivo</italic>. This method enabled autofluorescence imaging to monitor macrophage behavior in response to treatment, which would be helpful to identify new targets for drug development. Finally, <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fbioe.2020.00655/full">Wang et&#x20;al.</ext-link> present a rationally designed sandwich nanostructure of gold-graphene hybrid material that can be used for photoacoustic image-guided photothermal therapy. The imaging-guided photothermal therapy could precisely control the temperature of the tumor and potentially alter the TME through the disruption of its specific components.</p>
<p>As this Research Topic on this issue covers the recent advances in molecular and theranostic imaging of TME, it should be noted that the potential of nanotechnology and molecular imaging applications in imaging and modulation of TME has yet to be fully explored. The editors hope that the selected articles on this Research Topic will inspire future work to further advance and expand molecular and theranostic imaging in studying TME and beyond.</p>
</body>
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<sec id="s2">
<title>Author Contributions</title>
<p>All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.</p>
</sec>
<sec id="s1">
<title>Funding</title>
<p>This work received funding from the National Natural Science Foundation of China (Nos 82022034 and 81871420) and Jiangsu Province Natural Science Foundation of China (No. BK20200032).</p>
</sec>
<sec sec-type="COI-statement" id="s3">
<title>Conflict of Interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec id="s4" sec-type="disclaimer">
<title>Publisher&#x2019;s Note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
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