Born in Bucharest, she was the daughter of an Aromanian journalist and his Romanian wife. The Constante family left the city during the World War I German occupation, and Lena spent much of her childhood in Iaşi, Kherson, Odessa, London and Paris. Returning at the end of the conflict, she studied Painting at the Romanian Art Academy in Bucharest, and established friendships with leading intellectuals of her time, including Brauner, Mircea Vulcănescu, Petru Comarnescu, Henri H. Stahl, Mihail Sebastian, and Paul Sterian. During the period, she became sympathetic to left-wing politics and joined the sociological project initiated by Dimitrie Gusti, aiding in the creation of comprehensive monographs on traditional Romanian society; her visits to various villages acquainted her with traditional folk art, especially religious icons, which she later used as inspiration in her work. Constante first exhibited her art in 1934, and had personal shows in 1935, and 1946; her last exhibit before being arrested occurred in Ankara, Turkey. After 1945, she was employed as a stage designer by the newly founded Ţăndărică Theater, where she met Elena Pătrăşcanu, Lucreţiu's wife. In early 1946, when Pătrăşcanu, who was Romania's Minister of Justice, decided to go against the will of his party and intervened in the standoff between King Michael I and the Petru Groza executive, she mediated between him and two well-known anti-communist figures Victor Rădulescu-Pogoneanu and Grigore Niculescu-Buzeşti, in an attempt to ensure their support for a political compromise. Together with her friend Brauner, as well as Remus Koffler, Belu Zilber, Petre Pandrea, Herant Torosian, Ionel Mocsony Stârcea, the engineer Emil Calmanovici, Alexandru Ştefănescu and others, she was implicated in Pătrăşcanu's 1954 trial, being sentenced to twelve years in prison. The person who took initiative in bringing her to trial was Securitate deputy chief Alexandru Nicolschi. During repeated interrogations by the Securitate, Constante tried to fend off false accusations of "Titoism" and "treason", but, the victim of constant beatings and torture, and confronted with Zilber's testimony — which implicated her —, she eventually gave in and admitted to the charges. Throughout the rest of her life, she maintained a highly critical view of Zilber, and expressed her admiration for Pătrăşcanu, who had for long resisted pressures and had been executed in the end. As she stated in 2004,
"I did not know too well. It was not him that I went to jail. Neither was it Mrs. Elena . His friend, Belu Zilber, made us go to jail, me and my husband. Zilber was never pleased with all the things he kept inventing in his confessions and he would concoct some stuff that aimed to please the interrogators. To please Dej."
For much of her time in prison, Constante was kept in virtually complete solitude, a special regime which she later attributed to her earlier refusal to confess. Repeatedly beaten and again tortured during her stay in special prisons for women, she much later confessed that she was never able to forgive the people responsible for her plight. She was freed in 1962; in 1963, she married Brauner, who had also been released. They both were rehabilitated during Nicolae Ceauşescu's campaign of reviewing Romania's history under Gheorghiu-Dej. Constante exhibited her works on two other occasions. In 1990, after the Romanian Revolution, she published her French-language autobiography L'évasion silencieuse, at the Éditions La Découverte in Paris. The volume, which Vladimir Tismăneanu has compared to the works of Margarete Buber-Neumann, is written as a diary, and makes use of her prolific memory, which allowed her to record an immense succession of days, years after events had passed. It won the Prize of French-Language Writers' Association, and was translated into English as , with a preface by Gail Kligman; the Romanian version received the Romanian Academy's Lucian Blaga Prize. In 1993, she also published Evadarea imposibilă. Penitenciarul politic de femei Miercurea Ciuc 1957-1961. In 1997, Constante starred as herself in Nebunia Capetelor, a film by Thomas Ciulei based on The Silent Escape; Ciulei had originally intended to cast Maia Morgenstern as Constante, but ultimately decided to pay a special tribute to the book's theme.
